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damirchi--behzad
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Design, Manufacturing and Setting up the Injection and Mixing Teststand of Shear and Swirl injectors in Transcritical Condition
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
The arena of supercritical combustion involves a set of unique physical phenomena that are different from what is observed in the spraying and combustion of a subcritical regime. Understand the complex physics of the flow field in transcritical and supercritical operating conditions and discovery of factors affecting them and the extent to which each of these factors affects the structure of the jet and consequently the quality of the mixing and combustion process, is one of the basic steps to optimize of cryogenic liquid fuel engine combustion chamber design. In this thesis, by studying the experimental researches of injection at sub-critical to super-critical conditions, it has been tried...
Modeling and stability analysis of truncated high density lipoprotein (HDL) system using MARTINI coarse grain technique
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 3 A , November , 2013 ; 9780791856215 (ISBN) ; Rouhollahi, A ; Sohrabi, S ; Mehr, S. M. N ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2013
Abstract
Lipoproteins are biochemical compounds containing both proteins and lipids. These particles carry chemicals like cholesterol and triglycerides that are not soluble in aqueous solutions. This paper presents modeling of lipoprotein system using coarse grain molecular dynamics technique and stability analysis of this system in a water solution like blood. A high density lipoprotein (HDL) that consists of two annular monomers is modeled. Also there are lipid bilayers located in center of the rings, so the whole HDL and lipid bilayers are called lipoprotein system. First, all atom model is provided and then coarse-grain model is obtained using MARTINI technique. Modeling of the system in all atom...
An alternative mechanism for the formation of high density lipoprotein in peripheral tissue
, Article Scientia Iranica ; Volume 23, Issue 2 , 2016 , Pages 600-608 ; 10263098 (ISSN) ; Saidi, M. S ; Rismanian, M ; Firoozabadi, B ; Amininasab, M ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
High Density Lipoprotein (HDL) is a lipid-protein complex responsible for transporting cholesterol and triglyceride molecules, as these compounds are unable to dissolve in aqueous environments such as a bloodstream. Among the most well-known possible structures, the belt-like structure is the most common shape proposed for this vital bimolecular complex. In this structure, the protein scaffold encompasses the lipid bilayer and a planar circular structure is formed. Several HDL simulations with embedded components in the lipid section were performed. Here, we applied a series of molecular dynamic simulations using the MARTINI coarse grain force field to investigate an HDL model, with pores of...
Coarse Grain Molecular Dynamics Simulation of Drug Carrier Translocation into Cell Membrane
, M.Sc. Thesis Sharif University of Technology ; Saidi, Mohammad Said (Supervisor) ; Firoozabadi, Bahar (Supervisor)
Abstract
With the increasing development of the pharmaceutical industry and producing drugs with specific performance, its transfer into cells is also very important. Cell membranes are effectively impermeable to hydrophilic compounds unless the permeation is facilitated by dedicated transport systems. This means that many hydrophilic compounds, including many promising drug candidates, fail to reach their intracellular target because they cannot spontaneously cross lipid membranes. As a consequence, there is much interest in finding ways to facilitate the transport of molecules across cell membranes. Cell-penetrating peptides (CPPs) in particular have shown much promise as potential delivery agents...
A new method for detection of rolling bearing faults based on the Local Curve Roughness approach
, Article Polish Maritime Research ; Volume 18, Issue 2 , July , 2011 , Pages 44-50 ; 12332585 (ISSN) ; Bastami, A ; Sharif University of Technology
2011
Abstract
Detection of rolling bearing faults by vibration analysis is an important part of condition monitoring programs. In this paper a new method for detection of bearing defects based on a new concept of local surface roughness, is proposed. When a defect in the bearing grows then roughness of the defective surface increases and measurement of the roughness can be a good indicator of the bearing defect. In this paper a method of indirectly measuring surface roughness by using vibration signal is introduced. Several attached examples including both numerically simulated signals and actual experimental data show the effectiveness of the new, easy-to-implement method
Numerical and experimental investigation of the vibration of rotors with loose discs
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 224, Issue 1 , 2010 , Pages 85-94 ; 09544062 (ISSN) ; Asayesh, M ; Sharif University of Technology
2010
Abstract
In this study, the energy method has been used to develop a finite-element code for studying the effects of loose rotating discs on the rotor-bearing systems' response. A mathematical model of the loose disc has resulted in terms similar to unbalance and gyroscopic effects in the equation of motion of the system. Results of this study show that rotor response and beating phenomena are a function of measurement location, loose disc mass and inertia, ratio of rotating speed to the speed of loose disc, and clearance between the loose disc and shaft considering constant speed for loose disc and shaft. The developed finite-element model can numerically give the response of rotors with any number...
Friction-induced backward rub of rotors in non-annular clearances: Experimental observations and numerical analysis
, Article Tribology International ; Volume 152 , 2020 ; Alvandi, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
During backward rub in a turbomachine, rotor is compelled by frictional forces into a severe precessional sliding motion inside stationary parts such as seals or journal bearings in opposite direction of rotor's rotation. Backward rub occurs with high frequency and high amplitude of vibration and can deteriorates rubbing surfaces just for few moments. This paper presents and investigates the idea of clearance profile alteration from annular form to non-annular 3-lobed form in order to affect the reverse rub's characteristics. For this purpose, a test setup consisting of a lightly damped rotor-stator system is designed and built in SUT's condition-monitoring laboratory for testing the...
Unbalance-induced rub between rotor and compliant-segmented stator
, Article Journal of Sound and Vibration ; Volume 429 , 2018 , Pages 96-129 ; 0022460X (ISSN) ; Alvandi, M ; Sharif University of Technology
Academic Press
2018
Abstract
Today, turbomachinery designers are trying to attain zero clearances for optimizing performance and efficiency of machine by designing advanced compliant-segmented seals. This trend involves secondary issues such as rotor-to-stator contact interaction which is to be treated with more technical knowledge in rotordynamic design and condition monitoring programs. The aim of this paper is to gain insight into dynamic interaction between a flexible rotor and a set of compliant arc-shaped segments as stator system. Specifically, the unbalanced-induced forward rubbing response is investigated in tight clearance condition during resonance-passing situations. A Jeffcott rotor modeling is used for...
Experimental investigation on response and efficiency of moored pontoon type floating breakwaters
, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 31, Issue 1 , 2007 , Pages 95-99 ; 03601307 (ISSN) ; Akbari, M ; Sharif University of Technology
2007
Abstract
This paper presents the experimental results of an investigation on the response and efficiency of floating pontoon type breakwaters. Random waves modeled by the Pierson Moskowits wave spectrum are used for various configurations of floating breakwaters. The experimental results are presented in graphs for the transmission coefficient as a function of incident wave length and height for breakwaters used in this study. The obtained results for the breakwaters of this study show that by increasing the wave period and length, the transmission coefficient increases, while increase in the mass and draft of the floating breakwater causes the transmission coefficient to reduce. © Shiraz University
Fault Detection of Rotary System with Signal Processing and Intelligent Systems
, M.Sc. Thesis Sharif University of Technology ; 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...
Investigation of Magnetodielectric Resonator Antenna Including Gyroteropic Properties of Material
, M.Sc. Thesis Sharif University of Technology ; 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...
A Locality Aware P2P Overlay Architecture for Video Streaming
, M.Sc. Thesis Sharif University of Technology ; 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...
Condition Monitoring and Fault Diagnosis of Rolling Element Bearing in Phase Space
, M.Sc. Thesis Sharif University of Technology ; 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...
Analytical and Finite Element Modeling of Rubbing Phenomena in Rotors
, M.Sc. Thesis Sharif University of Technology ; 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...
Vibration Isolation of One Degree of Freedom Systems by Magnetorheological (MR) Damper Under Random Excitation
, M.Sc. Thesis Sharif University of Technology ; 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 ; 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...
Surface Integral Equations Technique for Ferrite Resonator Antennas
, M.Sc. Thesis Sharif University of Technology ; Rejaei, Behzad (Supervisor)
Abstract
So far, investigations have shown that open dielectricresonator antennas(DRAs) offer several advantages at microwaveand millimeter wave frequencies and make them appropriate in low directional-gain applications . 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 inthat their permeability tensor can be controlled by...
Design Software for Torsional Vibration of Gearbox
, M.Sc. Thesis Sharif University of Technology ; 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...
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...
Full Analysis Antenna Ferrite Disk in Range of Negative Permeability
, M.Sc. Thesis Sharif University of Technology ; 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,...
Identification of Vibrational Characteristic of System under Colored Excitation base on the Transmissibility Functions
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mehdi (Supervisor)
Abstract
Operational modal analysis (OMA) techniques are proper methods to identify the modal parameters of the structures such as natural frequencies, damping ratios and mode shapes based on the system responses. First research in this area are stared from civil engineering. Difference between civil structure and industrial machines are in the type of excitation.in most industries such as aerospace or mechanical, colored or harmonic forces due to rotary machines, excited the system. Under this condition, traditional methods in OMA are not capable any more. Many works has been done to modify traditional methods. Most of these work limited to situations that forces are harmonic and harmonic...