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motahari--morteza
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Total 258 records
Performance Based Analysis of Steel Bridges with Telescopic Dampers
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor)
Abstract
The main purpose of this study is Performance Based Analysis of steel bridges equipped with Telescopic Dampers and also to design a suitable damper in order to improve the behavior of the structural system and, consequently, reduce the damage to the structure after the earthquake. Different models of dampers such as Buckling Restrained Braces (BRB’s), Hydraulic Dampers, Viscous Dampers, Shear Panel Dampers, Visco-Elastic Dampers, etc., are used according to their specifications along with Laminated Rubber Bearings (LRB’s) to control the structural behavior of bridge, reduce deck displacement and base shear. The result of this project is the design of a special type of telescopic dampers,...
High Volume Event Correlation for Long-term Attack Detection
, M.Sc. Thesis Sharif University of Technology ; Amini, Morteza (Supervisor)
Abstract
The long-term Attacks are some special multi-level attacks which remain inside of systems for a long time to finally perform the damage. One of the most famous kinds of these attacks is Advanced Persistent Threats. These kinds of attack are low-level, distributed inside of the network and their goal is stealing information or corrupting a process in the organization. Banks are one of the most vulnerable organizations which have suffered from these attacks, so the main purpose of this research is detecting them and give warning to the security admin. The goal of financial APTs is stealing money and to achieve that, they have to create some transactions and send them to the core banking. We...
Android App Permission Analysis Based on Developer’s Privacy Policies
, M.Sc. Thesis Sharif University of Technology ; Amini, Morteza (Supervisor)
Abstract
With the increasing use of mobile smartphones, securing the information and protecting the mobile users’ privacy is one of the important subjects in this context. Android, as one of the most popular operating systems for smartphones, uses strategies to provide system security and user privacy; one of these strategies is permission system. Applications should get permissions from users to access their sensitive data. Most related researches and the android itself, focuses on granting or revoking permissions to the program in a way that it doesn’t misuse the user’s sensitive data, but most of the time, the purpose of accessing data is not obvious and the user doesn’t have enough knowledge...
Seismic Analysis of Multi-Degree Freedom Structures Equipped with Telescopic Metallic Yield Dampers (TLYD)
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor)
Abstract
Ordinary structures absorb a large amount of input energy by structural elements whereas failure in these elements causes a huge loss in structure and it’s really difficult to repair or unrepairable. Nowadays a wide range of metallic dampers is used in structures as fuse elements. this research evaluates the response of structures that are equipped with a novel steel damper named Telescopic Lead Yield Damper (TLYD) which was introduced by Eskandari in 2018. As TLYD has a different yielding plateau it can tolerate large deformations. In this research firstly this novel damper was introduced and the performance of the damper under cyclic loading was demonstrated. Then a numerical model of 6,...
Performance Improvement of Android Repackaged Applications
, M.Sc. Thesis Sharif University of Technology ; Amini, Morteza (Supervisor)
Abstract
Attacks on Android devices often take the form of repackaging. Attackers change a well-known app that has been downloaded from the app store, reverse engineer it, add some malicious payloads, and then upload the modified app to the app store. Because it is difficult for users to distinguish between the changed app and the original app, users can be easily duped. The malicious code inside the modified apps can launch attacks after they are installed, typically in the background. There are so many repackage detection method proposed during last years of researches in this area. developing an approach to detect android repackaged application should contains two main goal, speed and accuracy of...
Deep Learning and Optimal Control
, M.Sc. Thesis Sharif University of Technology ; Fotouhi, Morteza (Supervisor)
Abstract
Our main focus in this thesis is on optimal control methods for the analysis of deep neural networks, such as the supervised learning problem. A neural network with a large number of layers can be modeled with an ordinary differential equation, whose control parameters play the role of intermediary functions in the neural network. This model gives us a more powerful tool to analyze the asymptotic behavior of the neural network. Also, in this thesis, the problems of numerical implementation of these methods will be discussed
Mathematical Modeling and Simulation of Tumor Angiogenesis
, M.Sc. Thesis Sharif University of Technology ; Fotouhi, Morteza (Supervisor)
Abstract
A major medical revolution that is helping us overcome some of the worst diseases, including cancer, is angiogenesis, which is based on the processes our bodies use to develop blood vessels. Most human cancers have acquired six essential capabilities: self-sufficiency in growth signals, insensitivity to growth-inhibitory signals, programmed cell death escape, unlimited replication potential, persistent angiogenesis, and tissue invasion that can induce metastasis. In other words, the defense mechanism that prevents any of these acquired capabilities must be neutralized before the cells become malignant and invasive tumors. In fact, tumors in the non-vascular growth stage can only grow up to...
Preserving Privacy Through Intelligent Generation of Fake Events in Smart Homes
, M.Sc. Thesis Sharif University of Technology ; Amini, Morteza (Supervisor)
Abstract
Recently, the use of the Internet of Things (IoT) to enhance various environments has gained significant attention. With this technology's expansion into the realm of smart homes, IoT platforms have received considerable interest. These platforms help users implement automation rules by connecting a variety of smart devices and service providers. However, these platforms also have access to users' sensitive data, which could lead to privacy violations; this is because the data sent to the platform could be exploited by an attacker to extract patterns of user behavior. Current IoT platforms lack adequate measures to preserve user privacy, and furthermore, these platforms are not universally...
Impedance analysis of growth and morphology of electropolymerized polypyrrole nanocomposites [electronic resource]
, Article Journal of New Materials for Electrochemical Systems ; 2014, Volume 17, Number 2 ; Sadrnezhaad, S. K ; Sharif University of Technology
Abstract
Pure polypyrrole (PPy), PPy/Al2O3 and PPy/SiO2 nanocomposites synthesized galvanostatically using different polymerization charges. Electrochemical impedance measurements of pure polypyrrole revealed that the film thickness affected the impedance responses. The characteristic frequencies vs. film thickness that obtained using Cole-Cole plots showed that electrodeposition mechanism changed from 3D to 1D after nuclei overlapping for pure PPy. Analysis of the nanocomposites impedance spectrums revealed no changes during the film growth, i.e. deposition continues 3D even after nuclei overlapping. Scanning electron microscopy (SEM) confirmed the impedance results and showed that the morphology of...
Discrete kinematic synthesis of discretely actuated hyper-redundant manipulators
, Article Robotica ; Volume 31, Issue 7 , 2013 , Pages 1073-1084 ; 02635747 (ISSN) ; Zohoor, H ; Korayem, M. H ; Sharif University of Technology
2013
Abstract
Discrete kinematic synthesis of discretely actuated hyper-redundant manipulators is a new practical problem in robotics. The problem concerns with determining the type of each manipulator module from among several specific types, so that the manipulator could reach several specified target frames with the lowest error. This paper suggests using a breadth-first search method and a workspace mean frame to solve this problem. To reduce errors, two heuristic ideas are proposed: two-by-two searching method and iteration. The effectiveness of the proposed method is verified through several numerical problems
Van der Waals energy surface of a carbon nanotube sheet
, Article Solid State Communications ; Volume 152, Issue 3 , February , 2012 , Pages 225-230 ; 00381098 (ISSN) ; Shayeganfar, F ; Neek Amal, M ; Sharif University of Technology
2012
Abstract
The van der Walls interaction between a carbon nanotube sheet (CNTS) and a rare gas atom, is studied using both atomistic and continuum approaches. We present analytical expressions for the van der Waals energy of continuous nanotubes interacting with a rare gas atom. It is found that the continuum approach does not properly treat the effect of atomistic configurations on the energy surfaces. The energy barriers are small as compared to the thermal energy, which implies the free motion above the CNTS in heights about one nanometer. In contrast to the energy surface of a graphene sheet, the honeycomb lattice structure in the energy surface of a CNTS is imperceivable. Defects alter the energy...
A new obstacle avoidance method for discretely actuated hyper-redundant manipulators
, Article Scientia Iranica ; Volume 19, Issue 4 , August , 2012 , Pages 1081-1091 ; 10263098 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Elsevier
2012
Abstract
In this paper, a new method is proposed for solving the obstacle avoidance problem of discretely actuated hyper-redundant manipulators. In each step of the solution, the closest collision to the base is removed and then the configuration of the next part of the manipulator is modified without considering the obstacles. This process is performed repeatedly until no collision is found. The Suthakorn method is applied to solve the inverse kinematics problem. Two new ideas are proposed to reduce the errors of this method: the two-by-two searching method, and iterations. To verify the proposed method, some problems are solved numerically for 2D and 3D manipulators, each in two different obstacle...
A new motion planning method for discretely actuated hyper-redundant manipulators
, Article Robotica ; February , 2015 ; 02635747 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Cambridge University Press
2015
Abstract
A hyper-redundant manipulator is made by mounting the serial and/or parallel mechanisms on top of each other as modules. In discrete actuation, the actuation amounts are a limited number of certain values. It is not feasible to solve the kinematic analysis problems of discretely actuated hyper-redundant manipulators (DAHMs) by using the common methods, which are used for continuous actuated manipulators. In this paper, a new method is proposed to solve the trajectory tracking problem in a static prescribed obstacle field. To date, this problem has not been considered in the literature. The removing first collision (RFC) method, which is originally proposed for solving the inverse kinematic...
A new motion planning method for discretely actuated hyper-redundant manipulators
, Article Robotica ; Volume 35, Issue 1 , 2017 , Pages 101-118 ; 02635747 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Cambridge University Press
2017
Abstract
A hyper-redundant manipulator is made by mounting the serial and/or parallel mechanisms on top of each other as modules. In discrete actuation, the actuation amounts are a limited number of certain values. It is not feasible to solve the kinematic analysis problems of discretely actuated hyper-redundant manipulators (DAHMs) by using the common methods, which are used for continuous actuated manipulators. In this paper, a new method is proposed to solve the trajectory tracking problem in a static prescribed obstacle field. To date, this problem has not been considered in the literature. The removing first collision (RFC) method, which is originally proposed for solving the inverse kinematic...
Text Separation of Single-Channel Audio Sources Using Deep Neural Networks
, M.Sc. Thesis Sharif University of Technology ; Motahari, Abolfazl (Supervisor)
Abstract
The problem of separation of audio sources is one of the oldest issues raised in the field of audio processing, which has been studied for more than half a century. The main focus of recent research in this field has been on improving the sound quality resulting from the separation of sound sources with the help of deep neural networks. This is despite the fact that in most applications of audio source separation, such as the application of meeting transcription, we do not need the separated audio of people. Rather, we need a pipeline of converting overlapping speech to text, which, by receiving the audio in which several people have spoken, outputs the text spoken by the people present in...
Synthesis and Activity Test of Dehydrogenation Catalyst for C10-C14 Paraffin
, M.Sc. Thesis Sharif University of Technology ; Baghghalha, Morteza (Supervisor)
Abstract
Dehydrogenation of C10-C14 normal paraffins on Pt/alumina catalyst is a reaction of prime importance particularly to the detergent industry for the manufacture of the active ingredients. In this thesis, the modifying effect of Zn, Li, K, and Mg on the activity and selectivity of the Pt-Sn/γ-Al2O3 dehydrogenation catalysts were investigated. The catalysts were prepared by co-impregnation, characterized by TPR, BET, SEM, EDAX and XRD techniques and tested in a tubular reactor. Zinc reduced the activity of Pt-Sn alloy and hence reduced the catalyst activity in the dehydrogenation reaction and enhanced its selectivity to normal mono olefins. The addition of Li, K, and Mg to Pt-Sn/γ-Al2O3...
Electroplating Nano Crystalline Nickel for Reduction of Corrosion Rate
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor)
Abstract
Polycrystalline materials are solids that are composed of many crystallites of varying size and orientation called “Grain”. As the grain size reduces to the values below 100nm, the overall material properties are remarkably changed, and thus the resulting nanocrystalline materials have provided much better engineering properties at the same chemical composition compared to the microcrystalline. The main objective of the present study is to synthesize a nanocrystalline (22nm-25nm) coating based on Nickel over the yellow-brass plates. To do this, an electroplating technique in a modified Watts bath is employed in which the current density and stirring speed varied between 3 to 9.5 Ampere per...
Electroplating Nano Crystalline Acidic Zinc for Reduction of Corrosion Rate
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor)
Abstract
In this project, nonocrystalline zinc coatings with grain sizes within the range of 22-63 nanometers were produced on yellow-brass plates by electroplating in an acidic chloride bath in the presence and absence of additive has been investigated.current densities and bath stirring speeds change from 2 to 6 A/dm2 and 0 to 400 rpm respectively.To determine crystallite size, X-ray diffraction technique (XRD) was utilized;it was found that the use of additive has effectively refined the grain size and optimum current density is 3 A/dm2 to reach this objective.. it was observed that grain size increased continuously with increase in bath stirring speed. The results coming from XRD tests were...
Analysis and Conceptual Design of a Novel Metallic Yielding Damper
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor)
Abstract
In this thesis, three new metallic-yielding dampers for dissipation of energy in structures are introduced and studied. The advantages of dissipation of energy from torsional yielding in comparison to tensile yielding is verified by performing both monotonic and cyclic tests on three aluminum alloys specimens and a mild steel specimen. The experiments confirm that the energy absorption of steel in torsion is much higher than that in tension. Three different mechanisms are introduced to transform the axial movement into the torsional rotation. Each mechanism is studied in details. The first two mechanisms can be mounted at the end of bracings and the third one is installed at the...
Modeling and Simulating of Water Distribution in Different Layers of Direct Methanol Fuel Cell
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor)
Abstract
A two-dimensional, two-phase, nonisothermal model was developed in this work to investigate the water transport characteristic and water distribution in a direct methanol fuel cell (DMFC). Emphasis is placed on exploring the water distribution in different layers of DMF. The water and methanol crossover through the membrane were considered with the effect of diffusion, electro-osmotic drag, and convection. Governing equations including the prton and electron transport, continuity, momentum, species transport for methanol, water, and gases species, and the auxiliary equations are coupled to determine the output parameters. These parameters are the concentration distribution of the species,...