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Mechanical differences between ATP and ADP actin states: A molecular dynamics study

, Article Journal of Theoretical Biology ; Volume 448 , 2018 , Pages 94-103 ; 00225193 (ISSN) Mehrafrooz, B ; Shamloo, A ; Sharif University of Technology

Academic Press 2018

Abstract

This paper aims to give a comprehensive atomistic modeling of the nanomechanical behavior of actin monomer. Actin is a ubiquitous and essential component of cytoskeleton which forms many different cellular structures. Despite for several years great effort has been devoted to the investigation of mechanical properties of the actin filament, studies on the nanomechanical behavior of actin monomer are still lacking. These scales are, however, important for a complete understanding of the role of actin as an important component in the cytoskeleton structure. Based on the accuracy of atomistic modeling methods such as molecular dynamics simulations, steered molecular dynamics method is performed...

Dynamic analysis of an n-revolute planar serial manipulator and sensitivity analysis based on Sobol's method

, Article International Conference on Robotics and Mechatronics, ICROM 2015, 7 October 2015 through 9 October 2015 ; 2015 , Pages 569-574 ; 9781467372343 (ISBN) Mehrafrooz, B ; Mohammadi, M ; Masouleh, M. T ; Sharif University of Technology

2015

Abstract

In this paper, dynamic modeling and dynamic sensitivity analysis of an n-revolute planar serial robot are investigated. First, a dynamic modeling algorithm is proposed which is based on the concept of the so-called Natural Orthogonal Complement. The main goal of this algorithm consists in deriving the corresponding dynamic equations of a planar serial manipulator systematically. As a comparison study, 3-DOF a planar serial manipulator is modeled and the results of the proposed algorithm is compared with other methods, i.e., Newton-Euler, Lagrange-Euler, Adams software and an Open Dynamics Engine, the so-called MatODE. Then, in order to develop a dynamic sensitivity analysis scheme, Sobol's...

Molecular Dynamics Simulation of Actin: An Investigation into the Mechanical Properties

, M.Sc. Thesis Sharif University of Technology Mehrafrooz, Behzad (Author) ; Shamloo, Amir (Supervisor) ; Firoozbakhsh, Keikhosrow (Supervisor)

Abstract

Actin is the most abundant protein in most eukaryotic cells. It is highly conserved and participates in more protein-protein interactions than any known protein. Actin plays a crucial role in cell motility, adhesion, morphology and intracellular transport. Its biologically active form is the filament (F-actin), which is assembled from monomeric G-actin. In this thesis, the mechanical properties and characteristics of both G- and F-actin are studied using molecular dynamics simulations. In general, this thesis can be categorized into two individual parts: First, steered molecular dynamics simulation was performed to assess tension of monomeric G-actin molecule, and stress-strain curves were...

Workload-Aware Task Assignment in Real-time Fog-based Systems

, M.Sc. Thesis Sharif University of Technology Mehrafrooz Mayvan, Fatemeh (Author) ; Ejlali, Alireza (Supervisor) ; Ansari, Mohsen (Co-Supervisor)

Abstract

Cloud computing has provided a suitable platform for processing and storing Internet of Things data over the last few decades by establishing data centers with high processing power. Today, with the rise of real-time processing applications in the Internet of Things, such as voice assistants, smart health controls, and self-driving cars, the number of real-time tasks has increased rapidly; this is despite the fact that cloud servers cannot meet the deadline constraint due to physical distance delays. To address this challenge, Fog computing has been introduced. By moving computational and storage resources closer to the edge of the network, fog computing enables executing real-time tasks...

Setar Production Modification With Vibration Analysis

, M.Sc. Thesis Sharif University of Technology Mansour, Hossein (Author) ; Behzad, Mehdi (Supervisor)

Abstract

Setar is a traditional Persian musical instrument. Nowadays, Setar is one of the most common musical instruments in Persian music. A systematic method for Setar production modification has not been introduced yet. This work is the first scientific work about analysis of this instrument. The aim of this study is to undertake early steps for Setar quality improvement. In this thesis, after analysis of the wood using in Setar construction, numerical and experimental methods have been utilized to analyze this instrument. After that, some works has been performed to extract an objective function which can judge about Setar quality. The results show good agreement between experimental and...

Vibration Analysis of Edge Cracked Timoshenko Beam with Continuous Crack Model

, M.Sc. Thesis Sharif University of Technology Heydari, Mahdi (Author) ; Behzad, Mehdi (Supervisor)

Abstract

Structural defects such as cracks may be produced in structures and machineries under fatigue load operating conditions. The presence of crack can lead to catastrophic failures in certain conditions. The occurrence of cracks affects the dynamic and vibration behavior of the structure considerably. These vibrations can be used for identifying the cracks and appropriate actions can be taken to prevent more damage to the system. Therefore, in this thesis vibration analysis of a Timoshenko beam with a vertical and horizontal crack has been considered. A continuous model for vibration analysis of a beam with an open edge crack including the effects of shear deformation and rotary inertia has been...

Fault Detection of Rotary System with Signal Processing and Intelligent Systems

, M.Sc. Thesis Sharif University of Technology Tebyanian, Afshin (Author) ; Behzad, Mehdi (Supervisor)

Abstract

Condition monitoring and fault detection is an important way to provide economy in both time and costs. Many methods are developed for this purpose. Vibration analysis is one of the most important ways in this field. In this thesis, fault detection of mechanical rotary systems with nonlinear and non-stationary nature has been developed by use of empirical mode decomposition (EMD) and Hilbert transform. Firstly the measured signal is transformed into some intrinsic mode functions (IMF’s) by EMD, and then the Hilbert transform is implemented on each IMF. With Hilbert transform, the instantaneous frequency of system and then the mean frequency are obtained. Mean frequency is a key definition...

A Locality Aware P2P Overlay Architecture for Video Streaming

, M.Sc. Thesis Sharif University of Technology Bayat, Navid (Author) ; Akbari, Behzad (Supervisor)

Abstract

Internet video networks have already attracted millions of Internet users, and Internet video is one of the fast growing Internet services. The peer-to-peer (P2P) network is an efficient solution to supporting large scale video streaming on the Internet. P2P networks can deliver live multimedia content to millions of users with low cost at any time, and at anywhere they want. In this thesis, we investigate solutions to enhancing the performance of the unstructured mesh-based. Locality awareness or network proximity is one of the essential characteristics of P2P networks. In live P2P video streaming we face to some challenges like bandwidth heterogeneity of peers, and peer churn. In the P2P...

Analytical and Finite Element Modeling of Rubbing Phenomena in Rotors

, M.Sc. Thesis Sharif University of Technology Alvandi, Mahdi (Author) ; Behzad, Mahdi (Supervisor)

Abstract

Rotor contact with a stationary element of a rotating machine and the subsequent rubbing at the contact area is a serious malfunction that may lead to the machine’s catastrophic failure. In the past decades, many studies have been done on the rubbing phenomena, its different regimes and its various consequences on the machine performance and safety. However, most of them have used a simple model to investigate the rubbing interaction between the rotor and the stator. This simple model consists of the Jeffcott rotor, as a model for the real rotors, and a rigid annular block surrounding the rotor, as a model for the real stators. The objective of this thesis is to build an algorithm to...

Investigation of Magnetodielectric Resonator Antenna Including Gyroteropic Properties of Material

, M.Sc. Thesis Sharif University of Technology Naghdi, Behnam (Author) ; Rejaei, Behzad (Supervisor)

Abstract

So far, investigations have shown that open dielectric resonator antennas (DRAs) offer several advantages at microwave and millimeter wave frequencies. These advantages include small size, large impedance bandwidth, high radiation efficiency, ease of manufacturing and simple feed-coupling mechanisms (such as probe coupling, aperture coupling or proximity coupling to micro-strip lines). Most microwave ferrites have dielectric constants in the desirable range and they can be used in place of dielectric materials. Such ferrite resonator antennas (FRAs) offer a potential advantage in that their permeability tensor can be controlled by applying an external magnetic field. Up to now and by the...

Condition Monitoring and Fault Diagnosis of Rolling Element Bearing in Phase Space

, M.Sc. Thesis Sharif University of Technology Karimi, Majid (Author) ; Behzad, Mehdi (Supervisor)

Abstract

The failure in rolling element bearings as an important part of rotary machine can lead to machine breakdown.Consequently, bearings can reduce reliability of these components and therefore a maintenance strategy is essential to keep reliability in a desired level. The first and primitive strategy is called breakdown or unplanned maintenance. The next is preventive or planned maintenance. In this scheme, maintenance is done after a specified time period irrespective of machine health status. Out of place maintenance is the disadvantage of preventive maintenance. The most effective generation of maintenance strategy is condition based maintenance (CBM) which suggests maintenance decision based...

Vibration Isolation of One Degree of Freedom Systems by Magnetorheological (MR) Damper Under Random Excitation

, M.Sc. Thesis Sharif University of Technology Nakisa, Ali (Author) ; Behzad, Mehdi (Supervisor)

Abstract

The effect of Vibration on the human body is considered as one of the limitations in design and use of HSCs at high speeds. One way to reduce the effect of vibration on the human body is to isolate deck vibrations from the crew by means of seat suspension system. This thesis has studied the effect of using an MR damper on the performance of seat suspension in vibration reduction. In fact, employing MR dampers in seat suspension systems enables us to change their damping. Using an MR damper makes it possible to control seat suspension by semi active control strategies. In this work, a number of proposed mathematical models of an MR damper were studied for numerical analysis and the most...

Analysis of Losses in Articial Dilectric Waveguides at Mm-Wave Frequencies

, M.Sc. Thesis Sharif University of Technology Alizadeh, Arman (Author) ; Rejaei, Behzad (Supervisor)

Abstract

Today as various electronic and telecommunication devices like cell phones and PDAs are being popularized, MMIC technology is gaining a significant importance. One of the priorities of this technology is trying to miniaturize these popular devices. But reducing size of passive microwave components used in these devices requires microwave wavelength to decrease.Components fabricated by conventional deposition techniques aren’t thick enough to reduce the wavelength, so permittivities much higher than those of conventional dielectrics could be a possible solution. Artificial dielectric layers (ADL) can provide such high permittivities.So utilizing these layers can possibly reduce the size of...

Design and Implementation of a Robust Control Method for Rotor Tabilizing in a Three-pole Magnetic Bearing

, M.Sc. Thesis Sharif University of Technology Khansari, Saed (Author) ; Behzad, Mehdi (Supervisor)

Abstract

High speed and high accuracy are two of the major trends for many systems in the 21st century, such as machine tools and semiconductor equipment. For the purpose of high speed, it is well known that active magnetic bearing (AMB) is an inevitable substitute for conventional bearings. The noncontact nature of AMB brings up many advantages over the conventional bearing, including energy efficiency, low wearing, long life span, and absence of lubrication. Hence, AMBs are especially essential for high-speed rotating devices nowadays.
While the 3-pole AMB has been proposed for many years, it received little attention due to the magnetic coupling between poles that makes the 3-pole AMB system...

Theoretical Development of Resonance Acoustic Spectroscopy Technique and Its Applications for Non-destructive Evaluation of Thick-walled Cylindrical Shells

, Ph.D. Dissertation Sharif University of Technology Rajabi, Majid (Author) ; Behzad, Mehdi (Supervisor)

Abstract

Resonance acoustic spectroscopy (RAS) is one of the techniques used for monitoring the production quality and evaluation of mechanical properties of cylindrical components, due to their non-destructivity, high precision and quickness.
In this technique, the resonance effects are caused by the excitation of eigenvibrations of structure by an incident acoustic wave located in far-field. The resonance spectroscopy (isolation and identification of the resonance features) is performed on the far-field scattered pressure field which contains valuable information about the characteristics of the target. Appropriate exploitation of these resonance informations from the theoretical model and...

Finite Element Analysis of Buckling and Snaking Vibration for Drill String in the Horizental Well

, M.Sc. Thesis Sharif University of Technology Ansari, Amir (Author) ; Behzad, Mehdi (Supervisor)

Abstract

Snaking Vibration and buckling of drill string in the horizontal well was investigated in this research. Sinusoidal and helical critical buckling load are obtained for a specific drill string.
Drill string is modeled both analytically and numerically (finite element method). Drill pipes are considered as a clamped-clamped beam with constant cross section and the well is considered as a hollow cylinder. The thickness of cylinder was large enough to model the surrounding soil of the well. Buckling is a complex deformation and is somehow a random phenomenon. In addition, the length and the continuous contact between drill pipes and the well make the finite element model very huge and the...

Analysis and Simulation of Three-Dimensional Torsional Viscous Dampers

, M.Sc. Thesis Sharif University of Technology Matbou, Farshad (Author) ; Behzad, Mehdi (Supervisor)

Abstract

Torsional vibrations of internal combustion engines and reciprocating compressors, is one of the challenges in the design process. It can reduce power of productivity, equipment operating lifetime and increase noise of the system. Torsional viscous damper is a method to reduce torsional vibrations in rotating equipment. In this study, three-dimensional simulations of torsional viscous damper is performed as a matter of FSI, with consider harmonic excitation on the external walls and calculation of damping response inertia ring in CFX software. The viscoelastic non-Newtonian model properties of damping fluid is calculated in MATLAB software with respect to viscoelastic parameters. For...

Design Software for Torsional Vibration of Gearbox

, M.Sc. Thesis Sharif University of Technology Shahparasti, Masoud (Author) ; Behzad, Mehdi (Supervisor)

Abstract

Torsional vibration is undeniable in rotary systems, and it is more important in gearbox because it is the main cause of failure and noise. In this research The stiffness and damping between teeth are considered and mean stiffness between teeths are calculated by using material, contact ratio,and geometrical parameters. Transfer matrix method is used for obtaining natural frequencies and mode shapes.
In this thesis, effects of geometrical parameters of gears, backlash value, harmonic and constant torque on rattle noise show that increase in backlash, amplitude and frequency of excitation, magnify the power of impacts, also the time of rattle phenomenon and number of impacts decrease by...

Torsional Vibration Online Monitoring Design and Manufacturing

, M.Sc. Thesis Sharif University of Technology Samavatian, Mohammad (Author) ; Behzad, Mahdi (Supervisor)

Abstract

All rotating machines (such as internal combustion engines, reciprocating compressors, propulsion systems, etc.) experience torsional vibration during Start up, continuous working conditions and blackout. Torsional vibrationis due to pressure rhythms, engine dynamic torques, etc. All components of a rotating system must convey dynamic torque in addition to the static torque.Excessive Torsional vibrations cause wear and damage such as gears, gear teeth damage and failure to the main shaft.Online monitoring of torsional vibrations of the machine can be displayed machine condition at any moment and consider the risk in early diagnosis. Shaft torsional vibration monitoring can detect cracks in...

Full Analysis Antenna Ferrite Disk in Range of Negative Permeability

, M.Sc. Thesis Sharif University of Technology Ahmadvand, Ahmad (Author) ; Rejaei, Behzad (Supervisor)

Abstract

In wireless communication systems increasing the gain of antennas is seminal to increase in coverage and data transmission rate, and reducing the possible errors. One of the main factors for improving the antenna gain is matching the polarizations of the transmitter and the receiver antennas. Towards this end, both the transmitter and the receiver antennas should have the same axial ratio, specific direction and polarizations. As far as the flexibility of the direction angle between the transmitter and the receiver is concerned, the so-called circular polarization is preferred do the linear polarization. The antennas with circular polarizations are prominently utilized in satellites,...