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moghimi-najafabadi--mohammad
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Multiclass Visual Object Recognition Based On Cluttered Images
, M.Sc. Thesis Sharif University of Technology ; Kasaei, Shohreh (Supervisor)
Abstract
With the advancement of Machine Vision and Image Processing systems, the need for conceptual interpretation is raising. For this interpretation, one should detect objects available in the image and then tries to find the relations between the objects. For a good interpretation of the image, the machine vision system should learn patterns available in the nature. Object recognition systems are also used in other vision tasks and they can be used for content-based image retrieval, control and surveillance, or human action and gesture recognition for a better and easier human-computer interface. In an object recognition system, first some features should be extracted from the input image and...
Fast Centralized Model Predictive Control of Signal Splitting in Large Scale Urban Road Networks
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
With the rapid increase in the number of vehicles and the limitations on the extension of transportation network infrastructure, the need for utilizing proper methods to reduce traffic congestion has become increasingly important. One way to reduce traffic congestion is to control the signal splitting of traffic lights. Model predictive control (MPC) has been utilized so far by using different models of traffic flow dynamics in this field. Due to the high computational effort of MPC at each step time, the real-time implementation for large-scale networks has become a big challenge. Store-And-forward (SAF) is one of the traffic flow models that, due to its simplicity, makes it possible to...
Blood Glucose Control in Human Body Using Model-Based Controllers
,
M.Sc. Thesis
Sharif University of Technology
;
Shahrokhi, Mohammad
(Supervisor)
Abstract
Continous blood glucose control has great importance for type 1 dyabetic patients. In this thesis, several types of controllers including: PI controller, model predictive controller base on state space model, linear model predictive controller base of linear input-output model and non-linear model predictive controller base of Hammerstein model have been used to regulate blood glucose of patients with type 1 diabetes. These models are identified using least squars method. Performance of these controllers is tested and the best one is introduced. For rejecting meal disturbances, a feedforward controller has been designed. Combination of feedback and feedforward controller would properly...
Sandpile Model on Height Parameters
, M.Sc. Thesis Sharif University of Technology ; Moghimi Araghi, Saman (Supervisor)
Abstract
Many statistical systems such as earthquakes, road trafcs, forest fres, neurocortical avalanches etc. exhibit self-organized criticality (SOC). In such systems without tuning extrenal parameters, the system arrives at criticality. During recent decades, a number of models are introduced which show the same charactristics. These models have made a platform to investigate the physics of self-organized criticality. Among them, sandpile models are the best known models. They exhibit critical behaviour such as scaling laws. Also in some of them conformal invariance is checked nummerically.Most of sandpile models deal with slope parameters, that is, the main dynamical parameters are the local...
Simulation of Osteochondral Defect Treatment Using Cell Therapy
, M.Sc. Thesis Sharif University of Technology ; Abdekhodaei, Mohammad Jafar (Supervisor)
Abstract
This project investigates the simulation of osteochondral defect repair using cell therapy. The osteochondral defect is a common defect among people, where accident, age, and osteoporosis are the main causes of this defect. There are many treatment methods in clinics, which include the using bone allografts, drug treatments, and cell therapy. Cell therapy has been used in this project. For this purpose, firstly, the mathematical equations of the system are written and then the system is simulated using Python. In these equations, ten variables including chondrocyte cells, chondrocyte hypertrophy, osteoblast, different production matrices, and nutrients are used, which are written...
Water electrolyte transport through corrugated carbon nanopores [electronic resource]
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 90, Issue 1, July 2014, Article number 012304 ; Moosavi. A
Abstract
We investigate the effect of wall roughness on water electrolyte transport characteristics at different temperatures through carbon nanotubes by using nonequilibrium molecular dynamics simulations. Our results reveal that shearing stress and the nominal viscosity increase with ion concentration in corrugated carbon nanotubes (CNTs), in contrast to cases in smooth CNTs. Also, the temperature increase leads to the reduction of shearing stress and the nominal viscosity at moderate degrees of wall roughness. At high degrees of wall roughness, the temperature increase will enhance radial movements and increases resistance against fluid motion. As the fluid velocity increases, the particles do not...
Effects of Foundation Uplift on Seismic Performance of 2D Frames Placed on Flexible Foundation
, M.Sc. Thesis Sharif University of Technology ; Ghannad, Mohammad Ali (Supervisor)
Abstract
In conventional method of modeling and design of structures it is assumed that structures are fixedly supported, however, this assumption is generally far from reality; because, not only the majority of buildings’ bases are not stiff enough to suppose them rigid, but also if their foundations are shallow there exist no piles underneath them, they may separate from their bases – the event which is called foundation uplift. Although according to past studies permission of foundation uplift as well as incorporation of base flexibility may markedly affect any structure’s dynamic response, is spite of about half a century which has elapsed since the beginning of these studies, it seems that still...
Assessing Liquefaction Potential Based on Cone Penetration Test Results
, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
This study aimed to model the cone penetration test using FLAC 2D software in order to investigate the silty soils that can be found in tailing dams. Additionally, the model of the direct simple shear test was built in the software to estimate the variation of liquefaction potential in these soils with in-situ conditions. It should be noted that the constitutive law used in this study was the NORSAND model which meets the requirements of modeling in both tests. After validating the models, several important parameters are considered as variables to examine their effects on the results of both experiments. Regarding the validation of the models, the constructed numerical models of the cone...
Design, Construction and Experimental Study of the 3D Bending Device for spinal Column Stabilizing Rods
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor) ; Farahmand, Farzam (Supervisor)
Abstract
Deformity is one of the common diseases of the spine. For example, in the case of scoliosis, which is a three-dimensional deviation in the spine, the prevalence of 2% to 32% among adults has been reported [1]. In case of severe deformity, surgical methods are usually used to correct it. In surgical methods, rods with appropriate curvature are placed next to the spine and the deviation is completely or partially corrected by connecting the vertebrae to said rods. In general, the curvature of the rods is determined based on the clinical indicators of the patient, the tissue fault strength, the stiffness of the soft tissues, the movement limitation of the vertebrae and the level of spinal cord...
Gaussian Theory for Derivation of Continuum Equations of Self-propelled Particles
, Ph.D. Dissertation Sharif University of Technology ; Ejtehadi, Mohammad Reza (Supervisor) ; Moghimi, Saman (Co-Advisor)
Abstract
The collective behavior of active matters, e.g. colony of micro swimmers and flocks of birds is modeled with self-propelled particles. It is evident that a continuum description of such systems is useful in determining the collective behavior in large scales. One can make continuum equations in active matter with the help of symmetry arguments. However, the equation is in a phenomenological level with undetermined transport coefficients. It is possible to construct the continuum equations from microscopic rules to find the transport coefficients in terms of microscopic parameters with approximations. One of the usual approximations called truncation method is to truncate the Fourier series...
Continuous Transition from Self-organized Criticality to Self-organized Bistability
, M.Sc. Thesis Sharif University of Technology ; Moghimi Araghi, Saman (Supervisor)
Abstract
”Self-organized criticality” is a conceptual term that has helped us describe cer- tain critical behaviors in nature over the past approximately thirty years. In systems exhibiting this characteristic, critical behavior emerges without the need for external parameter adjustments. The necessary mechanism to observe such phenomena is for the critical point to be a dynamical attractor. Based on this, other phenomena have been proposed in which the critical point is not an attractor; instead, a stable cycle forms around it. This mechanism has led to the emergence of a new concept known as ”self- organized bistability.” The primary model proposed for such a phenomenon is based on a sandpile...
Investigation of Flow over a Fin Located Downstream of a Supersonic Jet into Subsonic Crossflow
, Ph.D. Dissertation Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor) ; Soltani, Mohammad Reza (Co-Advisor)
Abstract
The problem of jet into a cross flow is one of the classic problems in fluid mechanics and has many engineering applications, such as in vector thrust control systems. Although many works have been done in this field, there have not been enough research in interactions of supersonic jets into compressible subsonic cross flows (specially its interaction with control surfaces downstream). Hence, the purpose of this research is to get better understanding of this interaction and its effects on control surfaces downstream (both numerical and experimental). Some of the individual achievements of this research are the design and manufacturing of supersonic jet system, parametric study of: boundary...
Isoheight Line in Wolf- Villain Surface Growth Model With Using Schramm-Loewner Evoloution
, M.Sc. Thesis Sharif University of Technology ; Moghimi Araghi, Saman (Supervisor)
Abstract
Kinetic roughening has attracted a lot of attention over the last few decades not only because of its practical importance for the growth of solid films, but olso as an example for a dynamical mechanism
that drives a system into a spatially and temporally scale invariant state. Most of the models of kinetic roughening studies so far can be described by the KPZ equation. In this project growth processes which
cannot be described by KPZ will be studied. The first nonequilibrium growth models including deposition and surface diffusion were intruduced independently by Wolf and villain. The Schramm-Loewner evolution (SLE_, where _ is the diffusivity) proposed recently is a very successful...
that drives a system into a spatially and temporally scale invariant state. Most of the models of kinetic roughening studies so far can be described by the KPZ equation. In this project growth processes which
cannot be described by KPZ will be studied. The first nonequilibrium growth models including deposition and surface diffusion were intruduced independently by Wolf and villain. The Schramm-Loewner evolution (SLE_, where _ is the diffusivity) proposed recently is a very successful...
Investigation of the Performance and Properties of a New Generation Additives with Dual Purpose, Cell Opening and Delay Action Catalyst; in MDI and Polyester Polyol Based PU System
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Moghimi, Abolghasem (Co-Supervisor)
Abstract
Polyurethanes are polymers prepared by the reaction of polyols with isocyanates. Due to the wide range of raw materials from which polyurethanes are synthesized, as well as their various applications, they are classified into several groups, of which polyurethane foams are one of the most important products that have significant consumption. One of the most important diisocyanates is methylene diphenyl diisocyanate and also one of the most commonly used polyols in the polyurethane industry are polyesters.In addition, chain extenders, catalysts and suitable additives such as foaming agents, surfactants, fillers, etc., are all raw materials that participate in the production of polyurethane...
Secondary particles spectra in the decay of a polarized top quark with anomalous tWb couplings
, Article Journal of Physics G: Nuclear and Particle Physics ; Volume 34, Issue 1 , 2007 ; 09543899 (ISSN) ; Sharif University of Technology
2007
Abstract
An analytic expression for energy and angular dependence of a secondary charged lepton in the decay of a polarized top quark with anomalous tWb couplings in the presence of all anomalous couplings are derived. The angular distribution of the b-quark is derived as well. It is presented that the charged lepton spin correlation coefficient is not very sensitive to the anomalous couplings. However, the b-quark spin correlation coefficient is sensitive to anomalous couplings and could be used as a powerful tool in the search for non-SM coupling. © 2007 IOP Publishing Ltd
Semileptonic decay of a polarized top quark in the noncommutative standard model
, Article Physical Review D - Particles, Fields, Gravitation and Cosmology ; Volume 74, Issue 2 , 2006 ; 15507998 (ISSN) ; Sharif University of Technology
2006
Abstract
In this paper we study the noncommutative effects to the lepton spectrum from the decay of a polarized top quark. It is shown that the lowest contribution comes from the quadratic terms of the noncommutative parameter. The deviations from the standard model are significant for small values of the noncommutative characteristic scale. However, the charged lepton spin correlation coefficient has a remarkable deviation from the standard model from very low values of the noncommutative characteristic scale to 1 TeV. © 2006 The American Physical Society
Investigation of Io's auroral hiss emissions due to its motion in Jupiter's magnetosphere
, Article Research in Astronomy and Astrophysics ; Volume 12, Issue 6 , 2012 , Pages 693-702 ; 16744527 (ISSN) ; Sharif University of Technology
2012
Abstract
The left-hand side of the auroral hiss emission observed by Galileo has a frequency time profile shaped very similar to the funnel shape observed in the Earth's auroral region. This close similarity indicates that we can use the theory of whistler-mode propagation near the resonance cone to locate the emission source. The general characteristics of the whistler mode are discussed. Then the position of the emission source is investigated using a geometrical method that takes into account the trajectory of Galileo. Initially a point source is assumed. Then the possibility of a sheet source aligned along the magnetic field lines which are tangent to the surface of Io is investigated. Both types...
Welfare Cost of Fuel Subsidy to Manufacturing Firms
, Ph.D. Dissertation Sharif University of Technology ; Rahmati, Mohammad Hossein (Supervisor) ; Madanizadeh, Ali (Supervisor)
Abstract
This research aims to explore the effectiveness of past tariff evolutions in shaping firms' response to current input prices. Additionally, it investigates how asymmetric fuel pricing across different industries influences overall industry efficiency and prosperity. Furthermore, the study examines the impact of fuel subsidies on the equilibrium distribution of companies independent of welfare decline. In Chapter 1, utilizing microdata from Iranian industrial workshops between 1386-1396 (2007-2017) A key finding is that new firms exhibit a significant and stronger reaction to energy price variations compared to other firms when it comes to technology choices.Chapter 2 presents a structural...
Improvement of Software Quality Attributes based on the Properties of Relational and Non-relational data Models
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
With the growing use of computer systems, especially in form of web applications, software development and customer requirements has become more complex. Modern computer systems are supposed to achieve non-functional requirements in addition to functional requirements. Non-functional requirements are also called software quality attributes. One of the most important quality attributes for today's software systems is performance. Today’s softwares due to the growing number of their users, need more efficiency than ever to properly meet the performance request.Storage components and databases are the most important factors in causing performance bottlenecks in web applications. Most of...
Critical Behavior of Neuronal Systems: an Information Theory Viewpoint
, M.Sc. Thesis Sharif University of Technology ; Moghimi, Saman (Supervisor)
Abstract
Experiments conducted in recent two decades indicated critical behavior in neural activity at different scales. Theoretically occurrences of these critical and power-law behavior can significantly facilitate brain activities correspondent to computation and memory tasks, but attaining the critical point essentially demands externally fine-tuning which has not been established yet. This fine-tuning often lies with placing system at transition point. Recent studies of group showed that a transition from synchronous to asynchronous phase could be achievable by a change in external parameters. At the very transition point, neuronal avalanches statistically demonstrate a power-law behavior which...