Loading...
Search for:
aghapour--saeed
0.121 seconds
Total 678 records
Design and Security Analysis of Broadcast Authentication Schemes
, M.Sc. Thesis Sharif University of Technology ; Mohajeri, Javad (Supervisor)
Abstract
With the increase in the usage of wireless networks and smart grid networks and their applications, need for broadcast transmission has been increased dramatically. In order to use these communication, first we need to secure them by cryptographic methods. As authentication is one of the most important aspect of security, introducing secure broadcast authentication schemes are critical. Because of the resources constrainted nodes of these network, it is important to use light cryptographic methods with high security in these schemes. In this work, after analyzing related works, we introduce a new symmetric broadcast authentication scheme which is more efficient in term of memory consumption...
A Review of Practical Tests of Qantum Mechanics in Macroscopic Domain and its Relevance to the Measurement Problem
, M.Sc. Thesis Sharif University of Technology ; Golshani, Mehdi (Supervisor)
Abstract
The measurement problem is one of the issues that is still under debate about the Quantum theory. A significant part of literature during the recent years includes the standard point of view about this problem (including the separation of microscopic and macroscopic domains) and the criticisms of some major physicists in this context. Among these, alternative theories and interpretations have been getting more attention. Experimental tests of Quantum Mechanics in the macroscopic domain and their comparison with alternative theories have always encountered various difficulties (in particular the decoherence phenomenon). Anyway, towards the end of the last century, with the advances in...
On variational principle and canonical structure of gravitational theory in double-foliation formalism
, Article Classical and Quantum Gravity ; Volume 36, Issue 1 , 2019 ; 02649381 (ISSN) ; Jafari, G ; Golshani, M ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
In this paper, we analyze the variation of the gravitational action on a bounded region of spacetime whose boundary contains segments with various characters, including null. We develop a systematic approach to decompose the derivative of metric variations into orthogonal and tangential components with respect to the boundary and express them in terms of variations of geometric objects associated with the boundary hypersurface. We suggest that a double-foliation of spacetime provides a natural and useful set-up for treating the general problem and clarifies the assumptions and results in specialized ones. In this set-up, we are able to obtain the boundary action necessary for the variational...
A Machine Learning Approach to Minimize Power Consumption of Smartphones While Satisfying the Gaming Performance
, M.Sc. Thesis Sharif University of Technology ; Sarbazi Azad, Hamid (Supervisor)
Abstract
Today's smartphone devices include several cores, such as CPU, GPU, and different accelerators, in order to maximize user experience. However, due to meeting the power budget and limited capacity battery, power and energy of their cores should be managed using dynamic power management methods such as dynamic voltage and frequency scaling (DVFS). For this purpose, we should find optimal frequency and voltage settings of processing cores for each time, to minimize energy consumption while retaining user experience. Finding this optimal frequency and voltage settings is a challenging problem that depends on many parameters. We propose to use deep reinforcement learning (DRL) method to...
A multi sender attribute-based broadcast authentication scheme
, Article 2016 8th International Symposium on Telecommunications, IST 2016, 27 September 2016 through 29 September 2016 ; 2017 , Pages 78-83 ; 9781509034345 (ISBN) ; Ameri, M. H ; Mohajeri, J ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Multi sender attribute-based broadcast authentication scheme for the network containing resource constrained nodes is the main focus of this research. In this paper, we proposed a framework in which each element of a set of authorized users whose attributes satisfy a special sign control policy can generate a valid signature. In this framework, there exists a trusted server who receives and verifies the validity of the generated attribute-based signatures and broadcast the intended message through the nodes of the network in an efficient and authenticated manner. We also proposed a new symmetric-based broadcast authentication scheme which is used for broadcasting the authenticated messages...
Hardware Design for Cold Plasma Characterization Chamber
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan (Supervisor) ; Faez, Rahim (Supervisor)
Abstract
Cold plasma due to its special properties has many applications in the microelectronics industry. At the beginning of this study, a few examples of widely used plasmas and the requirements for driving their power sources have been investigated. To generate and characterize plasma, various topologies of DC power supply construction, including high-voltage low-current power supplies called multipliers and low-voltage high-voltage power supplies called converters, have been reviewed and compared.Circuit for pulse generating for plasma application has also been proposed and investigated. In the simulation section, after introducing, reviewing, and compareing the common types of simulators, the...
On the Concepts and Roles of Energy and Entropyin Gravitational Physics and Cosmology(Canonical Approaches in Definition of Conserved Quantities in Gravitational Physics)
, Ph.D. Dissertation Sharif University of Technology ; Golshani, Mehdi (Supervisor) ; Jafari, Ghadir (Co-Supervisor)
Abstract
In this thesis, inspired by foundational discussions about the concepts of energy and entropy in the gravitational theory, we study the definitions of these concepts and the roles they play in that theory. The definitions considered in this thesis are derived from canonical formalism. To this end, first of all, the variational principle and the canonical structure in the gravitational theory, especially in situations where the spacetime is bounded, is carefully studied and the boundary and corner actions as well as the canonical structure on the boundaries in three cases of non-null, null and general boundaries are derived. Based on this study, two canonical approaches, namely the...
A Bayesian-based classification framework for financial time series trend prediction
, Article Journal of Supercomputing ; Volume 79, Issue 4 , 2023 , Pages 4622-4659 ; 09208542 (ISSN) ; Manzuri, M. T ; Aghapour, A ; Karimi, A ; Rabiee, A ; Shalmani, S. M ; Sharif University of Technology
Springer
2023
Abstract
Financial time series have been extensively studied within the past decades; however, the advent of machine learning and deep neural networks opened new horizons to apply supercomputing techniques to extract more insights from the underlying patterns of price data. This paper presents a tri-state labeling approach to classify the underlying patterns in price data into up, down and no-action classes. The introduction of a no-action state in our novel approach alleviates the burden of denoising the dataset as a preprocessing task. The performance of our labeling algorithm is experimented with using machine learning and deep learning models. The framework is augmented by applying the Bayesian...
Performance of three-level spectrally encoded spreadtime CDMA in the presence of multiple interferences [electronic resource]
, Article IET Communications ; July 2011, Volume 5, Issue 10, P. 1328-1335 ; Mashhadi, Saeed ; Salehi, J. A ; Sharif University of Technology
Abstract
In this study the authors present an in-depth study, analysis and discussion on maximum likelihood (ML)-based receiver for a typical spectrally encoded spread-time CDMA in the presence of multiple narrowband interference (NBI) signals in an additive white Gaussian noise channel. Furthermore, the authors demonstrate that by combining useful properties of ML-based receiver and three-level codes, that is, codes with values of -1, 0, +1, the authors can introduce a new strategy in which superior performance with respect to previous receiver structure based on two-level codes, that is, codes with values of -1, +1, can be attained. With the help of an example, the authors drive, first, the...
Investigation of Multiphase Flow in Oil Wells (with Focus on Two Phase Flow), Flow Pattern Recognition and Modeling
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor) ; Jamshidi, Saeed (Supervisor)
Abstract
The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In oil and gas, production engineers often face a situation in which more than one phase is flowing through the producers. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between...
Casing Design Optimization Considering Drilling and Production Conditions
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Saeed (Supervisor) ; Shad, Saeed (Supervisor)
Abstract
Casing design is one of the most expensive parts in the drilling of oil wells, and any cost reduction with the basic design of these casing strings will significantly reduce the total cost of the operation. In recent years, occurring scenarios-based casing design has become popular; Because in many cases, it eliminates non-occurring scenarios such as gas kick and saves on drilling costs. In this study, we have tried to investigate all scenarios that may occur during the lifetime of the well, whether drilling or production, and for each well, based on its own field information, possible scenarios for each casing part are selected separately and the applying loads are calculated. For this...
PRI (Palm Rotation Indicator): a metric for postural stability in dynamic nonprehensile manipulation [electronic resource]
, Article Journal of MECHANIKA ; 2012, Vol. 18, No. 4, pp. 461-466 ; Meghdar, Ali ; Sohrabpour, Saeed ; Sharif University of Technology
Abstract
In this study, we discuss the postural stability of a nonprehensile manipulation problem, which deals with multibody objects. As a metric for postural stability, we define PRI. Then, the system is posturally stable, if PRI is inside the convex hull of the object-manipulator contact surface. We then discuss that dynamic biped locomotion is a special case of dynamic nonprehensile manipulation in all aspects; we prove that ZMP (zero-moment point) and FRI (zoot rotation indicator) are special cases of PRI (palm rotation indicator). Simulations and experiments corresponding to simple examples support the results
The Effect of a Critical Reflective Course on the Construction of Iranian EFL Learners’ Identity: A Case of an Online EFL Class
, M.Sc. Thesis Sharif University of Technology ; Rezaei, Saeed (Supervisor)
Abstract
The present study examines the effects of participation in a critical reflective online course upon the participants’ identity. The study drew upon both qualitative and quantitative research methodologies. The 38 participants of the study who were first degree students at Sharif University of Technology participated in ten online sessions in which ten prompts concerning intercultural issues were introduced. The data collected in the online course underwent inductive qualitative content analysis which resulted in the extraction of five themes. Following this, 18 participants were interviewed to throw more light on these findings. Qualitative and Quantitative content analyses of the data...
Preparation and Application of the Glassy Carbon Electrodes Modified with Carbon Nanomaterials for Studies of the Electrochemical Behavior and Quantitative Determination of Metoclopramide and Furazolidone
, M.Sc. Thesis Sharif University of Technology ; Shahrokhian, Saeed (Supervisor)
Abstract
In the first part, a novel electrochemical sensor based on nanocellulose-carbon nanoparticles (NC–CNPs) nanocomposite film modified glassy carbon electrode (GCE) is developed for the analysis of metoclopramide (MCP). The electrochemical behavior of MCP was investigated on the surface of the modified electrode using cyclic voltammetry (CV). Characterization of the surface morphology and properties of NC/CNPs was carried out by scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). Effective experimental variables, such as scan rate, pH of the supporting electrolyte, drop size of the casted modifier suspension and accumulation...
Study of ESP and Gas Lift Applications On low Productivity Wells of Alvand Oil Field
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Saeed (Supervisor)
Abstract
Alavand Oil field is located 50 Km away from west of Siri Island and includes DPG and DPH platforms. The production from Alavand field started in 1998 and till now 11 wells have been totally drilled .Since a production peak in 2001, the oil production in Alvand field has decreased. Water cut is increasing and reservoir pressure is decreasing gradually. Considering poor reservoir characteristic of this reservoir, productivity indexes of wells are relatively low. In addition; natural depletion of reservoir caused the wells to be unable to flow naturally and either closed or produce periodically consequently. To increase production and extend the lifetime of Alvand field, it is decided to start...
Real-time Vision-based Approach for Estimating Tool-tissue Contact Force with Application to Laparoscopic Surgery
, M.Sc. Thesis Sharif University of Technology ; Behzadipour, Saeed (Supervisor)
Abstract
Lack of force feedback during minimally invasive procedures is one of the downsides of such interventions and might result to excessive damage to surrounding tissues. The goal of the present research is to introduce a vision-based approach to estimate contact forces on soft tissues. In this approach, a model was developed in which, image of deformation of a sample soft tissue, under the jaws of laparoscopic gripper, is the input and the output is the gripper force. In this work, a FEM of soft tissue in contact with jaws of a laparoscopic tool is developed. . In the model, the effects of friction between the tool and tissue is considered which was not included in the previous studies. After...
Twin Edge Coloring of Graphs
, M.Sc. Thesis Sharif University of Technology ; Akbari, Saeed (Supervisor)
Abstract
Let G be a graph. A twin edge k-coloring of G is a proper edge coloring of G with the elements of Z_k so that for every vertex u and v of G we have s(u)≠s(v), where s(u) is the sum of all colors of the edges incident with u. The minimum k for which G has a twin edge k-coloring is called twin chromatic index of G and denoted by χ_t^' (G). In this thesis we find the chromatic index of paths, cycles, complete graphs, complete bipartite graphs and some complete tripartite graphs. In 2014 it was conjectured that if G is a connected graph with at least 3 vertices and maximum degree Δ(G), then χ_t^' (G)≤Δ(G)+3
Preparation and Investigation of the Electrochemical Behavior of Sensors Modified with Reduced Graphene Oxide nanohybrids for Electrochemical Determinations of Some Biologically Important Compounds
, M.Sc. Thesis Sharif University of Technology ; Shahrokhian, Saeed (Supervisor)
Abstract
In the first work, a stable composite film of silver nanoparticles decorated on reduced graphene oxide is easily prepared. The surface morphology of the modified electrode is characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The electrochemical behavior of TNZ on the surface of the modified electrode is investigated by using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The prepared modified electrode acts as a highly sensitive platform for the voltammetric determination of tinidazole (TNZ). Voltammetric investigations demonstrated that, in comparison to the glassy carbon electrode individually coated with...
Preparation of Nanocomposites from Carbon Nanostructures and Transtion Metal Oxides and their use in Preparation of Hybrid Electrochemical Capacitors
, M.Sc. Thesis Sharif University of Technology ; Shahrokhian, Saeed (Supervisor)
Abstract
In the first part, we report a new and simple procedure for preparing reduced graphene oxide /nickel, cobalt hydroxide composite (Ni,Co-OH/rGO/NF via a fast and simple two-step electrochemical method including potentiostatic routes in the presence of Cetyl trimethyl ammonium bromide )CTAB( as a cationic surfactant. In the first step, a piece of nickel foam (NF) is sonicated in a suspension of graphene oxide (GO, 6 mg/L) after dried in an oven, reduced by electrochemically. After that, Ni, Co LDH were co-deposited on the surface of rGO/NF. The resulting modified electrode afforded extremely high specific capacitance of 2133.3 F/g at a current density of 4 A g-1. FE-SEM results showed that...
Electrochemical Sensors Based on Electrodes Modified with Composites of Carbon Nanostructures and Polypyrrole; Application to Electrochemical Investigations and Determination of Nifedipine and Tizanidine
, M.Sc. Thesis Sharif University of Technology ; Shahrokhian, Saeed (Supervisor)
Abstract
In the first part, the electropolymerization of pyrrole was performed in the presence of Titan Yellow (TY) as a dopant anion on the surface of the electrode precoated with CNTs. The modified electrode was used to study the voltammetric response of tizanidine (TIZ). A remarkable increase was observed in the anodic peak current of TIZ on the surface of the modified electrode relative to the bare GCE. The surface morphology PPY/CNT/GCE was thoroughly characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. Under the optimized analysis conditions, the modified electrode showed two linear dynamic ranges of 0.01 - 1 μM and 1-10 μM with a detection limit of 3 nM...