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amini-noghondar--reza
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Experimental Determination of Damping and Stiffness of a Rolling Element Bearing
, M.Sc. Thesis Sharif University of Technology ; Mohammad Navazi, Hossein (Supervisor)
Abstract
This thesis aims to provide a method to obtain the radial dynamic properties of rolling element bearing, including stiffness and damping by experimental test methods. Methods such as modal test, vibration test, and static tests were known as experimental methods to obtain these properties, and in this research, all three of these methods were used to obtain these properties. After studying the theoretical relations governing the stiffness coefficients of the bearings, a test bed platform was designed and built to conduct the tests After the construction of this platform, the test design stage was reached done and different parameters changed during these tests several tests were it is noted...
Optimal Control of Batch Cooling Crystallizers Using Inversion Approach
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
In batch cooling crystallization, the crucial control problem is to design a temperature trajectory which produces a desired crystal size distribution. Here, a completely different solution is presented. Designing model-based controller for crystallizer has two steps; first step is determining optimal temperature trajectory which is some kind of feedforward control, second step is adding feedback controller (with manipulated variable of jacket temperature or cooling flow) to track the set-point (determined in first step) and rejecting possible disturbances. Traditionally, determining optimal temperature of crystallizer is done by using calculus of variations of distributed system. In this...
Sol-Gel Preparation and Study of Bio-Composite Scaffold Containing Chitosan-Gelatin/ Nano-Hydroxyapatite for Bone Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
In present work, hydroxyapatite nano-rods are synthesized using a simple sol-gel method with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus precursors respectively and ammonia was used for adjusting the pH=9. To obtain rod shape hydroxyapaite powder, multi wall carbon nanotubes were added to the solution, nHA powder was calcinated at 60 and 450 ℃. In second step, chitosan-gelatin/nanoHA solution were prepared by blending chitosan and gelatin in different concentrations with nanoHA powder, then the solution was freeze dried to maintain a composite scaffold. The prepared HA powder and bio-composite scaffold were characterized by X-ray diffraction (XRD), field...
Thermo-Hydro-Mechanical Modeling of Fractured Porous Media with phase Change
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
The main goal of the research is to formulate and implement the governing equations of Thermo-Hydro-Mechanical (THM) phenomena in fractured/fracturing unsaturated porous media with two-phase fluid flow using the Extended Finite Element Method (XFEM)with phase change consideration(evaporation/condensation). The medium is assumed to be isotropic, and the fluid phases are liquid water, vapor and dry air. The four governing equations are linear momentum equilibrium of the media, continuity equation of water (liquid water and vapor), continuity equation of dry air, and the thermal equilibrium of the medium which are considered to be fully coupled. The fracture is modeled in mode I with...
Processing and Characterization of Fracture Behavior of Hybrid Epoxy Nanocomposite Modified with Polycarbonate
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor)
Abstract
Epoxy resins have good mechanical and thermal properties, high chemical resistance and low shrinkage during cure but in spite of these good properties,they are brittle and this limits the usage of them. Adding a second, soft or rigid, phase has been always an effective strategy to improve the toughness of epoxy. Rigid phase used in resins are divided into organic and inorganic. The aim of this study is to increase epoxy toughness, maintaining mechanical properties and study effect of silica and polycarbonate on fracture toughness simultaneously. Mechanical properties including yield strength and elastic modulus are evaluated by pressure test. Additionally fracture toughness and three...
Sustainable Reverse Logistics Network for Separated Recyclable Household Waste
, M.Sc. Thesis Sharif University of Technology ; Akbari Jokar, Mohammad Reza (Supervisor)
Abstract
In this study we addressed the problem of separated waste management. Investigating the literature on location routing problem, reverse logistics, waste management, and countries’ performance in the field, we proposed a novel method for gathering household waste that inspired from prosperous metropolises and took into account the particular situations of developing countries. As a matter of fact, the proposed method is an extension of location routing problem; it’s a bi-echelon network of facilities and multi-compartment vehicles connected via reverse cross docks. The problem is formulated using a mixed-integer linear model with 3 economic, social, and environmental functions; with respect...
Prediction of Customer Churn From Subscription Services in Response to Recommendations: With Emphasis on MCI Data
, M.Sc. Thesis Sharif University of Technology ; Amini, Arash (Supervisor) ; Kazemi, Reza (Supervisor)
Abstract
In competitive markets where a product or service is provided by multiple providers, as the telecom market, keeping active users is expected to be less expensive than attracting new users. In this regard, first of all, churning should be predicted for active users, and secondly, proper recommendations should be provided to prevent churning. In this thesis, by modeling customer churn as a response to the recommendations, we study the churn prediction and prevention problem as a recommender system. This model enables us to select the best offer for each user to prevent it from churning.Modeling customer churn in a recommender system introduces new challenges, including delay in observing...
Characteristics of Liquid Crystal Near a Flat Surface Using EES Potential
, M.Sc. Thesis Sharif University of Technology ; Ejtehadi, Mohammad Reza (Supervisor)
Abstract
The study of the interaction between ellipsoid particles and the flat wall is the basis for understanding phenomena such as the passage of colloidal particles through the membrane and the order resulting from the presence of the wall in liquid crystals. Previous studies on liquid crystal systems confined between two walls have shown that topological constraints and the surface interaction of particles with the wall change the order behavior and create a surface layer near them. The thickness of this surface layer is about a few molecules, and this helps to achieve the result observed in the laboratory, in computer simulations. LAMMPS software is one of the most powerful codes available for...
Continuous-time Mean-Variance Portfolio Selection with Partial Information
, M.Sc. Thesis Sharif University of Technology ; Moghadasi, Reza (Supervisor) ; Zamani, Shiva (Co-Advisor)
Abstract
In this thesis, we study a continuous time financial market of some risky assets and a risk-free asset for investment in a finite time period. We use mean-variance approach for investment in this market. In the model considered here, the mean returns of individual assets are explicitly affected by underlying Gaussian economic factors. Using past and present information of the asset prices, a partial-information stochastic optimal control problem with random coefficients is formulated. Here, the partial information is due to the fact that the economic factors can not be directly observed. In first step, by filtering and in secound step by solving the stochastic control problem, we show that...
Unsupervised Anomaly Detection in Mobile Networks
, M.Sc. Thesis Sharif University of Technology ; Amini, Arash (Supervisor) ; Kazemi, Reza (Supervisor)
Abstract
With the fast-growing mobile networks, the need for network reliability increases. Various events like antenna failures, attacks on mobile networks, floods, sporting events cause abnormal behavior in mobile networks. Some events like antenna failures and attacks need consideration. But some of them like sporting events can be ignored. Right now, most mobile operators, detect these events manually which is a very time-consuming and costly task for them. To overcome this problem one idea is to predict future data by prediction algorithms. Then compare new data with the predicted one. If there exists significant deviation, there is an anomaly. But most of the failures and anomalies in mobile...
Robustification of Deep Learning Structures Based Ongenerative Models
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Reza (Supervisor) ; Amini, Sajjad (Supervisor)
Abstract
In recent years, deep learning has experienced rapid and remarkable advancements, demonstrating exceptional performance in various applications such as computer vision, natural language processing, and autonomous vehicles. These models are continually evolving and expanding, yet they harbor inherent vulnerabilities that prevent complete trust in their reliability. One of the most critical issues is their susceptibility to adversarial attacks, where a clean image is subtly manipulated to create an adversarial example. Adversarial examples, generated by adding imperceptible perturbations to input data, can easily mislead deep learning models into making highly confident yet incorrect...
Theoretical Analysis of Mechanical Properties for Metal Matrix Nanocomposites Reinforced by Carbon Nanotubes Using Nonlocal Elasticity
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
Abstract
Nanocomposites are fabricated by incorporating nano-scale particles in polymer, metal, or ceramic matrices. Metal matrix nanocomposites are a new kind of materials which have shown superior mechanical features, such as high strength, stiffness, and hardness. However, they are not sensitive to high temperature, in contrast to the polymer matrix nanocomposites. Nanoporous materials, also, have wide range of applications in different fields, such as geology, biology, biomechanics, and electronic. Carbon Nanotubes (CNTs) have shown wonderful properties like high Young’s modulus, high resonance frequency and unique electrical behavior. Wonderful mechanical and electrical properties make CNTs...
Sliding Motion of Carbon Nanotube on Graphene Surface
, M.Sc. Thesis Sharif University of Technology ; Ejtehadi, Mohammad Reza (Supervisor) ; Nikamal, Mahdi (Co-Advisor)
Abstract
Unique and interesting properties of Graphene with two dimentional and CarbonNanotubes rod-like and their increasing applications such as application in electronic industry, sensors, displays, supercapasitors, pharmacy, etc, they hase become an important field of condensed matter and nanotechnology. Crystalization process and the distribution of light atoms and molecules on graphene surface hase become one of the reaserche arease of interest and hase attracted much attention. These studies play an important role in design of nanosensors graphene based. Most of the experimental observatins of surface diffusion in the chemical and physics systems have been classically described and...
A Lattice based Secret Sharing Scheme with Changeable Threshold
,
M.Sc. Thesis
Sharif University of Technology
;
Aref, Mohammad Reza
(Supervisor)
;
Eghlidos, Taraneh
(Co-Advisor)
Abstract
The need to protect the key in cryptosystems has been a motivation of studying secret sharing schemes. A secret sharing scheme is a method for sharing a secret data (key) by distributing some values, called shares, to a number of participants in such a way that only some authorized subset of them can recover the secret. In a threshold secret sharing scheme, authorized subsets are those whose size are at least a given value called threshold of the scheme. Increasing the attacker capabilities in achieving the participants’ shares, requires an increase in the threshold parameter. In a changeable threshold secret sharing scheme, participants ate able to compute new shares from their old shares...
Hippocmapal Protein Kinase Mζ Overexpression Effect on Cognitive Performance in a Rat Model of Alzheimer’s Disease
, M.Sc. Thesis Sharif University of Technology ; Roosta Azad, Reza (Supervisor) ; Gholamipour Badie, Hamid (Supervisor)
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disease which results in synaptic depression and complete destruction in neurons in the final stages. Many pathogenesis has so far been attributed to AD but the most commonly explained pathomechanism is based on the amyloid cascade theory which results in formation of amyloid beta plaques outside and hyper phosphorylated neurofibrillary tangles of tau protein inside the neurons. One of the most well-known symptoms of AD is the disability to learn and form new memories and transform them into long term memory. The most commonly studied mechanism in memory formation, is the “long term potentiation”. Although many mechanisms and molecules are...
Municipal Wastewater Treatment Using Microalgal-Sludge System
, M.Sc. Thesis Sharif University of Technology ; Shaygan Salek, Jalaloddin (Supervisor) ; Mehrnia, Mohammad Reza (Supervisor)
Abstract
If wastewater is not properly treated, then the environment and human health can be negatively impacted. These impacts can include harm to fish and wildlife populations, oxygen depletion and contamination of drinking water. In the typical wastewater treatment process, the goal of primary, secondary and tertiary effluent treatment is to reduce or remove organic matter, solids, nutrients, disease-causing organisms and other pollutants from the treated wastewater before it is discharged to a body of water. Biological methods for wastewater treatment are much preferable for being more economical and environmentally friendly. Biological treatment of wastewater using algal-bacterial culture...
Copper(II) acetate
, Article Synlett ; Volume 23, Issue 13 , 2012 , Pages 1995-1996 ; 09365214 (ISSN) ; Sharif University of Technology
2012
Abstract
(A) Chakraborty and co-workers have developed a green method for the bulk ring-opening polymerization of lactides in the presence of Cu(OAc)2 as a good catalyst to synthesize polymers with different end-terminal groups.3 These polymerizations are highly controlled leading to the formation of polymers with the expected number of average molecular weights and narrow molecular weight distribution. (B) Garden and co-workers have found that the oxidative addition of anilines with 1,4-naphthoquinone to give N-aryl-2-amino-1,4-naphthoquinones can be performed in the presence of catalytic amounts of copper(II) acetate.4 All the reactions are generally more efficient in that they are cleaner, higher...
Solving rank one revised linear systems by the scaled ABS method
, Article ANZIAM Journal ; Volume 46, Issue 2 , 2004 , Pages 225-236 ; 14461811 (ISSN) ; Sharif University of Technology
2004
Abstract
In mathematical programming, an important tool is the use of active set strategies to update the current solution of a linear system after a rank one change in the constraint matrix. We show how to update the general solution of a linear system obtained by use of the scaled ABS method when the matrix coefficient is subjected to a rank one change. © Australian Mathematical Society 2004
Dextran-graft-poly(hydroxyethyl methacrylate) gels: A new biosorbent for fluoride removal of water
, Article Designed Monomers and Polymers ; Volume 16, Issue 2 , 2013 , Pages 127-136 ; 1385772X (ISSN) ; Mousavi, S. A ; Amini Fazl, A ; Amini Fazl, M. S ; Ahmari, R ; Sharif University of Technology
2013
Abstract
Synthesis of dextran-graft-poly(hydroxyethyl methacrylate) gels as a new fluoride biosorbent was considered in this work. For this propose, the Taguchi experimental design method was used for optimizing the synthetic conditions of the gels to reach high level of fluoride absorbency. The effects of three main parameters including concentrations of monomer (hydroxyethyl methacrylate), crosslinking agent (ethylene glycol dimethacrylate), and initiator (ammonium persulfate) on the final properties of the prepared gels were investigated. The proposed mechanism for grafting and chemically crosslinking reactions was proved with equilibrium water absorption, Fourier-transformed infrared, scanning...
Optimization of synthetic conditions of a novel collagen-based superabsorbent hydrogel by Taguchi method and investigation of its metal ions adsorption
, Article Journal of Applied Polymer Science ; Volume 102, Issue 5 , 2006 , Pages 4878-4885 ; 00218995 (ISSN) ; Salimi, H ; Amini Fazl, M. S ; Kurdtabar, M ; Amini Fazl, A. R ; Sharif University of Technology
2006
Abstract
A novel biopolymer-based superabsorbent hydrogel was synthesized through chemical crosslinking by graft copolymerization of partially neutralized acrylic acid onto the hydrolyzed collagen, in the presence of a crosslinking agent and a free radical initiator. The Taguchi method, a robust experimental design, was employed for the optimization of the synthesis reaction based on the swelling capacity of the hydrogels. This method was applied for the experiments and standard L16 orthogonal array with three factors and four levels were chosen. The critical parameters that have been selected for this study are crosslinker (N,N′-methylene bisacrylamide), initiator (potassium persulfate), and monomer...