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Improved H2 production from the APR of polyols in a microreactor utilizing Pt supported on a CeO2–Al2O3 structured catalyst

, Article International Journal of Hydrogen Energy ; Volume 43, Issue 48 , 2018 , Pages 21777-21790 ; 03603199 (ISSN) Entezary, B ; Kazemeini, M ; Sharif University of Technology

Elsevier Ltd 2018

Abstract

In this research, the activity and selectivity of a platinum-based catalyst for H2 production through aqueous phase reforming (APR) in a fixed-bed reactor (FBR) as well as, a structured catalyst microreactor (MR) were investigated. In this venue, first, an in-house designed MR was fabricated and the catalytic material was deposited on the channel walls of this steel made reactor. After verification of the stability of the coated layer, the prepared reactor was employed to investigate the APR reaction. In this regard, APR of the ethylene glycol and glycerol over Pt/Al2O3 and Pt/CeO2–Al2O3 catalyst were conducted in an MR and FBR. Obtained results demonstrated that employing Pt/CeO2–Al2O3 as a...

Aqueous Phase Reforming of Biomass Using Micro-reactor

, M.Sc. Thesis Sharif University of Technology Entezary, Behzad (Author) ; Kazemeini, Mohammad (Supervisor) ; Mohammadi, Aliasghar (Supervisor)

Abstract

Consumption of oil and gas as energy carrier leads to irreversible environmental effects related to greenhouse gases emission. Hence, for the reduction in greenhouse gas emission, a shift to renewable resources for energy supply is recommended. However, in recent years, hydrogen has emerged as the most promising clean energy carrier for generating electrical power through fuel cells. Nevertheless, production of renewable hydrogen is the main barrier to the development of hydrogen as an energy carrier. Aqueous phase reforming of oxygenated hydrocarbon is developed by Dumesic for producing renewable hydrogen-rich gas with low CO. Since it is expected that, use of new technology such as the...

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,...

Surface Integral Equations Technique for Ferrite Resonator Antennas

, M.Sc. Thesis Sharif University of Technology Norouzzadeh, Elham (Author) ; 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...

Development of a Three Layer Model for Simulating Transient Behavior Cutting Transport in Extended-reach Well

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

Abstract

A major concern in directional well drilling is the transport mechanism of cuttings by drilling fluid. This thesis describes the effect of angular velocity and postbuckled vibrations of drillstring on cuttings transport in a directional well drilling. The analysis proceeds in two stages. First, a finite element model is used to predict the dynamic behavior of postbuckled drillstring inside a directional well. Second, a coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) approach to simulate the cuttings transport considering the dynamic collision process. In the combined computational fluid dynamics and discrete element method (CFD-DEM), the fluid phase is treated...