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moghadasi--jamshid
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Experimental Investigation of Mud-Induced Formation Damage in Fractured Reservoirs
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davood (Supervisor) ; Moghadasi, Jamshid (Supervisor)
Abstract
Productivity reduction of oil and gas wells due to mud induced permeability impairment is one of challenging problems in drilling and production studies. This phenomenon is of prime importance in fractured reservoirs in which high permeability fracture networks act as conduits for feeding gas or oil from a tight matrix to the wellbore. Up to now, many experimental and modeling investigations have been done in formation damage in conventional reservoirs. But in spite of large contribution of fractured reservoirs in total hydrocarbon reserves, there is very little work reported in the literature investigating formation damage in such reservoirs. In this thesis, the effective parameters in...
Comparison of Rheological Properties of Slurry with International Standards to Evaluate the Successfulness of Gachsaran Oil Field Cementation and Proposing Experimental Solutions
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Sirous (Supervisor) ; Moghadasi, Jamshid (Supervisor)
Abstract
The rheology of oil well cement (OWC) slurries is generally more complicated than that of conventional cement paste. In order to contend with bottom hole conditions, a number of additives are usually used in the OWC slurries. The objective of this research is to develop a fundamental understanding of the important mechanisms that affect the properties of OWC slurry such as rheological properties, free water, compressive strength and thickening time incorporating various chemical and mineral admixtures. The partial replacement of OWC using different nanoparticle weight percent has been proved to be a promising method. The mechanisms underlying the effects of chemical admixtures on the...
Experimental Investigation of Factors Affecting Formation Damage through Aqueous Phase Trapping in Gas Reservoirs
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Moghadasi, Jamshid (Supervisor)
Abstract
Aqueous phase trapping (APT) in many of the oil and gas reservoirs is a significant mechanism of formation damage during drilling, completion, work over, and stimulation operation. APT can limit the productivity of the well to a high extent, especially in low permeable gas reservoirs. Experimental investigation of factors affecting APT is vital to recognize extends of associated damage and contribution of each factor. Albeit many experimental studies have been conducted as regards factors affecting removal of phase traps in understudy mechanism of formation damage, but up to date no experimental data has been published regarding effect of different factors on reservoir’s potential for APT....
Deep Compositional Captioner
, M.Sc. Thesis Sharif University of Technology ; Esfahani Zadeh, Mostafa (Supervisor) ; Kamali Tabrizi, Mostafa (Co-Supervisor) ; Moghadasi, Jamshid (Co-Supervisor)
Abstract
One of the most important applications of artificial intelligence, and especially deep learning is image captioning. Given an image, the task is to automatically produce a sentence, describing the image. Image captioning has several real world applications like helping the blind understanding the images, generating automatic captions for the social media, etc. In the past, several different methods for image captioning have been used, but after the emergence of deep learning, like many other areas, image captioning algorithms have been improved significantly. In this thesis, I talk about a specific method for image captioning, called ”Deep Compositional Captioning. In this method, at first...
Experimental Investigation for FINDING a Suitable Additive (Nanoparticle) to Design Required Elastic Cement for Iranian Oil/Gas Wells
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Soltanian, Hamid (Supervisor) ; Moghadasi, Jamshid (Supervisor) ; Samsam Sokheiravi, Mohammad (Co-Advisor)
Abstract
Previous studies indicate that increasing cement compressive strength can’t prevent loss of zonal isolation and casing collapse in worse case during well operations or formation loading. Since standard cements with high compressive strength can’t solve these problems, so application of elastic cements with low Young’s modulus and high Poisson’s ratio becomes important. These cements sustain generated stresses during well operations and prevent creation of point loads when formation creep occurs. For this purpose, a new additive was designed in order to improve the cement elasticity and tensile strength. It is a nanoparticle and named EX-RIPI (by Research Institute of Petroleum Industry,...
Failure Modes Analysis and Mechanisms for Life Extension of Gas Turbines
, M.Sc. Thesis Sharif University of Technology ;
Abstract
Currently, the relatively long time of the turbine life passes and their parts and equipment damage are different, that loss optimum performance and thus reducing their efficiency and may lead to faults and other unexpected stops in their production cycle. Process used to estimate the remaining life of the various components of this turbine is an important tool for improving the efficiency of these units to perform preventive maintenance. In the present thesis, the types of damages in different parts of gas turbines and various methods for detection of critical points, particularly finite element method, high cycle fatigue, modal analysis, methods to estimate the lifetime of a gas turbine...
Polar decomposition of the k-fold product of lebesgue measure on ℝ n
, Article Bulletin of the Australian Mathematical Society ; Volume 85, Issue 2 , 2012 , Pages 315-324 ; 00049727 (ISSN) ; Sharif University of Technology
2012
Abstract
The Blaschke-Petkantschin formula is a geometric measure decomposition of the q-fold product of Lebesgue measure on ℝ n. Here we discuss another decomposition called polar decomposition by considering ℝ n× ×ℝ n as n×k and using its polar decomposition. This is a generalisation of the Blaschke-Petkantschin formula and may be useful when one needs to integrate a function g:ℝ n××ℝ n→ℝ with rotational symmetry, that is, for each orthogonal transformation O,g(O(x1),O(xk))=g(x1,xk) . As an application we compute the moments of a Gaussian determinant. Copyright
Controllability of rolling bodies with regular surfaces
, Article Journal of the Korean Mathematical Society ; Volume 53, Issue 4 , 2016 , Pages 725-735 ; 03049914 (ISSN) ; Sharif University of Technology
Korean Mathematical Society
2016
Abstract
A pair of bodies rolling on each other is an interesting example of nonholonomic systems in control theory. There is a geometric condition equivalent to the rolling constraint which enables us to generalize the rolling motions for any two-dimensional Riemannian manifolds. This system has a five-dimensional phase space. In order to study the controllability of the rolling surfaces, we lift the system to a six-dimensional space and show that the lifted system is controllable unless the two surfaces have isometric universal covering spaces. In the non-controllable case there are some three-dimensional orbits each of which corresponds to an isometry of the universal covering spaces
Rolling of a body on a plane or a sphere: A geometric point of view
, Article Bulletin of the Australian Mathematical Society ; Volume 70, Issue 2 , 2004 , Pages 245-256 ; 00049727 (ISSN) ; Sharif University of Technology
Australian Mathematical Publishing Association
2004
Abstract
A pair of bodies rolling on each other is an interesting example of nonholonomic systems in control theory. Here the controllability of rolling bodies is investigated with a global approach. By using simple geometric facts, this problem has been completely solved in the special case where one of them is a plane or a sphere
Forward and Inverse Problem of Seismic Waves
, M.Sc. Thesis Sharif University of Technology ; Moghadasi, Reza (Supervisor)
Abstract
Applying of seismic waves and analysing of its reflections is of effective ways in exploration of the internal structur of the Earth. In this method the Earth is considered as a elastic body that seismic waves are propagated in it. In this thesis the how of creation and propagation of seismic waves is modeld at first and then the inverse problem, exploration of the internal structure of the Earth from observed data, is considered
Trajectory Estimation of a Vehicle Using Stereo Cameras
, M.Sc. Thesis Sharif University of Technology ; Moghadasi, Reza (Supervisor)
Abstract
Visual odometry(VO) is the process of estimating the egomotion of an agent(e.g., vehicle, human, and robot) using the input of a single or multiple cameras attached to it. Application domains include robotics, wearable computing, augmented reality, and automotive. The term was chosen for its similarity to wheel odometry, which incrementally estimates the motion of a vehicle by integrating the number of turns of its wheels over time. Likewise, VO operates by incrementally estimating the pose of the vehicle through examination of the changes that movements induces on the images of its onboard cameras. For the VO to work effectively, there should be sufficient illumination in the environment...
Ray Tracing Based on Reinforcement Learning
, M.Sc. Thesis Sharif University of Technology ; Moghadasi, Reza (Supervisor)
Abstract
We show that the equations of reinforcement learning and light transport simulation (rendering equation) are related integral equations. Based on this correspondence, a scheme to learn importance while sampling path space is derived. The new approach is demonstrated in a consistent ray tracing algorithm that uses reinforcement learning to progressively learn where light comes from. As using this information for importance sampling includes information about visibility, too, the number of light transport paths with non-zero contribution is dramatically increased, resulting in much less noisy images within a fixed time budget
Doc2vec Natural Language Model of Farsi
, M.Sc. Thesis Sharif University of Technology ; Moghadasi, Reza (Supervisor)
Abstract
Due to immense increase in availability of text data, interest in using machine learning models to solve problems previously impossibly costly has increased significantly. The first step is to represent natural language in a form that is easy for the machine learning algorithms to work on. Recent advances in learned representation of text data using simple neural networks(e.g. word2vec and doc2vec) helped increase performance of natural language processing on downstream tasks. Here we show that methods like doc2vec that were examined mostly in the English language can be used on Persian(Farsi) with little modification. To Demonstrate this, we use text classification tasks, and train...
Feasibility Study of Culturing and Differentiating Mesenchymal Stem Cells to Smooth Muscle Cells in Nanostructured PCL Hybrid Scaffold
, M.Sc. Thesis Sharif University of Technology ;
Abstract
Tissue engineering is an interdisciplinary field that incorporates principles of engineering with the life sciences. Tissue engineering consists of three principle; cells, scaffolds for cells expansion and growth factors. These factors together can help tissue engineers to provide appropriate microenvironments for directing special cells behavior.
Fibrous scaffolds have found many applications in tissue engineering due to their nanometer dimensions and high surface to volume ratio. Fibrous scaffolds can impart mechanical strength, structure for cell attachment and act as reservoirs for biomolecule delivery in much a same way as the natural fibrous components of the extracellular...
Fibrous scaffolds have found many applications in tissue engineering due to their nanometer dimensions and high surface to volume ratio. Fibrous scaffolds can impart mechanical strength, structure for cell attachment and act as reservoirs for biomolecule delivery in much a same way as the natural fibrous components of the extracellular...
Preparation and Characterization of Chitosan-Gelatin/Polyanilne-Graphene-CNT Nanocomposite for Neural Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor)
Abstract
Repairing and regeneration of neural tissues have attracted considerable attention due to its direct effect on the quality of patients’ lives. Recent developments in nanotechnology and tissue engineering have facilitated their comprehensive applications in the treatment of neurological diseases, and several effective ways have been proposed to repair defects in neural tissues. The main objective of the researches in this field is to regulate cellular behavior and tissue progression through the design and development of synthetic extracellular matrices, such as novel biomaterials, that enhance cell culture and tissue regeneration. Natural polymers, such as chitosan and gelatin, are suitable...
Enhancing Opinion Mining in Social Networks using Graph-based Analysis
, M.Sc. Thesis Sharif University of Technology ; Moghadasi, Reza (Supervisor)
Abstract
In the past, opinion polls have generally been conducted using statistical techniques and the comments of those samples, which, in addition to its various challenges, require much power and cost per poll. Today, due to the high penetration rate of social networks in society, a very large fraction of people discuss such issues in terms of their opinions and preferences in these networks, and hence, these networks can be a valuable source of information to get the opinions of people in a short time, and by lower cost.The purpose of this thesis is to enhancing the results of the surveys which have already performed using various methods of text processing in social networks by using the graph...
Semi Supervised Approaches for Image Depth Estimation
, M.Sc. Thesis Sharif University of Technology ; Moghadasi, Reza (Supervisor)
Abstract
One of the important tasks in machine vision is 3D structure reconstruction or depth estimation. In recent decades, methods based on machine learning have been presented, which can be used to perform this costly task more optimally. For this purpose, two branches of supervised and unsupervised learning have been considered. In supervised learning, the available data is in the form of image-depth map pairs, such as the kitti dataset. The image is fed to the network and the output is made in the form of a depth map. The cost function of this network is obtained by comparing the generated depth map and the depth map in the data set calculated by laser. In unsupervised learning, there is no...
Optimal attitude consensus for multi rigid bodies network considered on the lie group SO(3) with connectivity preserving property
, Article IET Control Theory and Applications ; Volume 16, Issue 11 , 2022 , Pages 1137-1153 ; 17518644 (ISSN) ; Sojoodi, M ; Moghadasi, S. R ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
This paper proposes distributed optimal attitude consensus control for single-integrator multi rigid bodies with undirected network evolving on Special Orthogonal Group SO(3) while simultaneously guarantees the connectivity preservation property for agents using descent gradient algorithm. Since by Use of the Euclidean distance on Lie group as a measure of the energy of the state does not define and preserve the topology of SO(3); besides, solving the Hamilton–Jacobi–Bellman equation in optimal control problems shows difficulty implementing Euclidean distances and limits the results for SO(3) configuration state spaces. As a result, in this paper, the generic distance on SO(3) associated to...
Tournaments
, M.Sc. Thesis Sharif University of Technology ; Mahmoodian, Ebadollah (Supervisor) ; Moghadasi, Reza (Supervisor)
Abstract
In this thesis which is an extensive expository and survey, we study concepts like irreducible, primitive, regular and almost regularournaments. We study and show the proof of some graph theoretical properties of tournaments such as being pancyclic, vertex or arc-pancyclic, and a lower bound on the number of cycles of each length in irreducible tournaments. Spectral properties and the Perron eigenvalue of tournament matrices are also extensively discussed.The ranks of tournament matrices over different algebraic fields, is another subjectthat is covered. We have written computer programs to study the distribution of the rank of tournament matrices over Z2.With a little more work,one might...
Hippocampal shape analysis in epilepsy using Laplace-Beltrami spectrum
, Article 2011 19th Iranian Conference on Electrical Engineering, ICEE 2011, 17 May 2011 through 19 May 2011 ; May , 2011 , Page(s): 1 - 5 ; ISSN : 21647054 ; 9789644634284 (ISBN) ; Soltanian Zadeh, H ; Moghadasi, S. R ; Sharif University of Technology
2011
Abstract
Shape analysis plays an important role in many medical imaging studies. One of the recent shape analysis methods uses the Laplace Beltrami eigenvalues which is also used in this paper for global shape comparison of hippocampus of normal subjects and epileptic patients. Popularity of the Laplace Beltrami operator in this field is due to its isometry-invariance which avoids pre-processing steps like mapping, registration, and alignment. In addition, it is capable of revealing fine details in shapes that makes this method a good choice for deformation detecting purposes like epilepsy diagnosis. To examine capability of the proposed method, statistical analysis and two ways of classification,...