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mousavi-abarghouie--mohammad-reza
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Investigation of the Effect of Temperature on Wear Behavior of 2024Al and 2024Al-20vol.%SiCp Composite
, M.Sc. Thesis Sharif University of Technology ; Seyyed Reihani, Morteza (Supervisor)
Abstract
In this research, friction and wear behaviors of 2024 Al and 2024 Al-20 vol.% SiC composite -prepared by powder metallurgy method- were investigated in the temperature range 20- 250°C. Dry sliding wear tests were conducted at a constant sliding velocity of 0.5 m/s, an applied load of 20 N, and a sliding distance of 2500m using a pin-on-disc apparatus. Some of the wear tests were carried out with artificially aged specimens in order to determine the aging effects. Worn surfaces and wear debris were also examined by using SEM, EDS and XRD techniques. All specimens showed a transition from mild to severe wear above a critical temperature. In the mild wear regime, the wear rate and the friction...
Aging behavior of a 2024 Al alloy-SiCp composite
, Article Materials and Design ; Volume 31, Issue 5 , May , 2010 , Pages 2368-2374 ; 02641275 (ISSN) ; Seyed Reihani, S.M ; Sharif University of Technology
2010
Abstract
In the present research work the 2024 aluminum alloy was reinforced with SiC particles via powder metallurgy method. The effect of heat treatment conditions on artificial aging kinetics was investigated. The solution treatment of the composite sample and the unreinforced alloy was carried out at 495 °C for 1, 2 and 3 h followed by aging at 191 °C for various aging times between 1 and 10 h. The existence of SiC particles led to increasing the peak hardness of the alloy. The peak hardness of the composite sample took place at shorter times than that of the unreinforced alloy for the samples solution treated for 2 and 3 h, but took place at longer times for the samples solution treated for 1 h....
Investigation of friction and wear behaviors of 2024 Al and 2024 Al/SiCp composite at elevated temperatures
, Article Journal of Alloys and Compounds ; Volume 501, Issue 2 , Jan , 2010 , Pages 326-332 ; 09258388 (ISSN) ; Seyed Reihani, S. M ; Sharif University of Technology
2010
Abstract
Friction and wear behaviors of artificially aged 2024 Al and 2024 Al/20 vol.% SiC composite prepared by powder metallurgy method were investigated in the temperature range 20250 °C. Dry sliding wear tests were conducted at a constant sliding velocity of 0.5 m/s, an applied load of 20 N, and a sliding distance of 2500m using a pin-on-disc apparatus. Worn surfaces and wear debris were also examined by using SEM and EDS techniques. All specimens showed a transition from mild-to-severe wear above a critical temperature. In the mild wear regime, the wear rate and the friction coefficient of the composite specimen were higher than those of the unreinforced alloy. The SiC particles led to an...
Migrating From 3D Modelling of the Laser Assisted Machining Process into a Valid 2D Model
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
Due to recent advances in laser technology and instruments, laser assisted machining processes has gained extra attention by scientists and industries. Naturally, effective modeling of the process is of great interest for researchers. Machining processes are generally modeled via FE tools and based on the requirements of model, it can be performed either mechanically or thermos-mechanically. About the LAM problems, it is basically meaningless to have a model without considering thermal effects. Hence, modeling is performed in two steps where through the first one, a thermal problem is solved to bring the temperature distribution of the work piece as the initial conditions of the next step....
Experimental Study of the Effect of Liquid Fluid Injection Conditions Inside the Evaporation Tube on its Performance
, M.Sc. Thesis Sharif University of Technology ; Morad, Mohammad Reza (Supervisor)
Abstract
This reaserch is study on the performance of evaporation tubes used in mini jet engines which has been done experimentally using laboratory equipment. In this study, researchers have tried to simulate the laboratory conditions as much as possible to the real conditions inside the mini-jet engine, increase the accuracy of the results and increase the results and bring them closer to the results inside the mini-jet engine. The experiments are divided into two categories, cold and hot In cold tests, an attempt is made to study and investigate the types of two-phase flow regimes created by applying different fluid and air flow rates, and to select annular flow regimes from among them....
Simulation and Analysis of of NEM Relays for Low Power VLSI Applications
, M.Sc. Thesis Sharif University of Technology ; Sarvari, Reza (Supervisor)
Abstract
Over the past five decades, the proliferation of electronic devices and the advent of Internet of Things (IoT) technology have ushered in a profound revolution in integrated circuit technology. In contemporary electronics, digital integrated circuits rely predominantly on CMOS transistors. Among the notable limitations associated with CMOS transistors are their non-zero off-state current and limited sub-threshold slope. In response to these limitations, researchers have ventured into a burgeoning field known as "Beyond CMOS," exploring technologies like Tunnel Junctions, Carbon Nanotube FETs, and more. Additionally, alternative approaches that blend electronic and mechanical principles in...
Design And Fabrication of Proper Meta-Material Structure For Substituting Lumbar Herniated Disc
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
As humans age, the intervertebral discs in the spine lose some of their water content, reducing their flexibility and making them more prone to tears in the annulus fibrosus. When the annulus fibrosus weakens, the disc's nucleus can push through and cause a herniation, which can press on surrounding nerves and lead to severe pain. Each surgical method for treating disc herniation has its own complications and challenges. The gold standard treatment is fusion surgery, which fixes two vertebrae together, preventing natural movement in that part of the spine. This altered stress distribution on adjacent vertebrae can ultimately damage adjacent healthy discs over time. This research aims to use...
Improvement in Reinforced Concrete Beam-Column Connections Behavior using Steel Plates
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Ali Reza (Supervisor)
Abstract
Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In this research, using steel plates for seismic upgrading of Concrete Beam-Column connections subjected to axial and cyclic loads has...
Aging behaviors of Al 6061 and Al 6061/ SiCp composite
, Article Advanced Materials Research ; Volume 410 , 2012 , Pages 240-244 ; 10226680 (ISSN) ; 9783037853160 (ISBN) ; Ekrami, A ; Seyed Reihani, S. M ; Mousavi Abarghouie, S. M. R ; Sharif University of Technology
2012
Abstract
In the present research the aging behavior of Al6061 alloy and Al6061/SiCp composite fabricated by powder metallurgy method was investigated. The solution treatment of the samples were carried out at 527°C for 2, 3and 4 h followed by aging at 180°C for different aging times between 1 and 10 h. The existence of SiC particles led to increasing the peak hardness of the composite. The peak hardness of the composite took place at shorter times than that of the 6061 alloy for the samples solution treated for 3and 4 h, but took place at longer times for the samples solution treated for 2 h. The optimum solution treating time was about 3 h for both the composite and the 6061 alloy that led to the...
Improvement of Security Features of Communication Networks with Network Coding
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Salmasizadeh, Mahmoud (Supervisor)
Abstract
In this thesis, we study security features of the networks which use linear network coding to multicast information to some nodes of the network in presence of a wiretapper and also an active intruder. We consider information theoretic security in which we assume no computation limits for enemy. Thus, we take advantage of the essence of network coding instead of cryptographic tools to improve security features of the network. First, we show how providing shannon security for such networks in presence of wiretapper, leads to different cost in multicast rate, depending on initial network code designed. Based on this, we present a modified secure network code design which can provide perfect...
Pore Scale Simulation of the Fluid/Fluid and Fluid/Rock Interactions on the Performance of Water Injection
, M.Sc. Thesis Sharif University of Technology ; Fatemi, Mobin (Supervisor) ; Pishvaie, Mahmood Reza (Co-Supervisor)
Abstract
Two-phase fluid flow physics in porous media is applied in various fields. Studies have shown that wettability and surface tension, which represent fluid-rock and fluid-fluid interactions, have a significant effect on the dynamics of the immiscible displacement. Although the effects of wettability and surface tension on the macroscopic behavior of fluid flow are known, there is less understanding of it at the micro scale. Considering the essential role of wettability and surface tension in various fields, this project seeks to investigate the effects of wettability and surface tension on the movement and distribution of fluids and the dominant displacement mechanisms within the porous media...
A misbehavior‐tolerant multipath routing protocol for wireless Ad hoc networks [electronic resource]
, Article International Journal of Research in Wireless Systems (IJRWS) ; Vol. 2, Issue 9, pp. , Sep. 2013 ; Pakravan, Mohammad Reza ; Aref, Mohammad Reza ; Sharif University of Technology
Abstract
Secure routing is a major key to service maintenance in ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. As a result of the resource limitations in such networks nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a novel data redirection method to mitigate the impact of node misbehavior on network...
Non-Parametric Analysis of Positional data of a Micro-Nano Sphere Trapped by Optical Tweezers
, M.Sc. Thesis Sharif University of Technology ; Reihani, Nader (Supervisor) ; Rahimi Tabar, Mohammad Reza (Supervisor)
Abstract
Optical tweezers consist of a tightly focused laser beam. A particle with refractive index greater than that of the surrounding medium can be trapped at the focus of the laser. The trapped object experiences a three-dimensional Hookean restoring force towards the focus. Nano (micron)-sized spheres can produce forces in the range of few pico-newton to few nano-newton. This range covers a large number of the forces, which contribute in biological processes; therefore, optical tweezers are very often used for micromanipulation of biological tissues. In a typical micromanipulation experiment it is crucial to perform proper positional calibration prior to use. There are several calibrate methods...
Numerical Modeling of Density-Driven Flow in Vuggy Porous Media Using Extended Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
The main goal of this research is to investigate the effects of different types of heterogeneities on fluid flow and solute transport in saturated porous media. These heterogeneities are micro- and macro-fractures and cavities. For modeling micro- and macro-fractures we used an equivalent continuum model and extended finite element, respectively. Also, we modeled the problem by using mass conservation law for both components of the problem – fluid flow and the solute – and Darcy’s law. In modeling vuggy porous media, due to the high velocity of the fluid inside the free flow areas i.e. channels and cavities, we could not model the medium properly using Darcy’s law. Therefore, we had to use a...
Physical-Phenomenological Constitutive Modeling and Numerical Analysis of Magnetic Shape Memory Alloys
, M.Sc. Thesis Sharif University of Technology ; Arghavani, Jamal (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Naghdabadi, Reza (Co-Advisor)
Abstract
Magnetic shape memory alloys (MSMAs) are a new class of smart materials that exhibit characteristics of large recoverable strains and high frequency. These unique characteristics, make MSMAs interesting materials for applications such as actuators, sensors, and energy harvesters. This thesis presents a three-dimensional phenomenological constitutive model for MSMAs, developed within the framework of irreversible continuum thermodynamics. To this end, a proper set of internal variables is introduced to reflect the microstructural consequences on the material macroscopic behavior. Moreover, a stress-dependent thermodynamic force threshold needed for variant reorientation is introduced which...
Controllability of Networked Systems based on Structural Features of Proximity Graphs
, Ph.D. Dissertation Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
Recently, there has been a surge of research activities in the area of networks in the systems and control community. One foundational class of questions on networked systems pertains to their controllability. While there are classical tests to check the controllability of linear time-invariant (LTI) systems, their applications to large-scale networks is numerically infeasible. Indeed, finding a minimum cardinality set of input nodes that ensure the controllability of a network is NP-hard. Moreover, when the interaction strengths along the edges of a network are unknown, the classical controllability test cannot be applied. To overcome these issues, an alternative set of approaches involves...
Modeling of Large Deformation Frictional Contact Using the Augmented-Lagrange Method
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
The numerical modeling of engineering contact problems is one of the most difficult and demanding tasks in computational mechanics. Frictional contact can be observed in many problems; such as: crack propagation, metal forming operation, drilling pile etc. In metal forming operations the required shape changes are obtained by either of forming process, such as pressing, hammering, rolling or extruding the material between the tools which are much stiffer than shaped material. Because of large difference between deformability of the tool and material, relative movements occur in contact area. These relative movements produce the normal and tangential stresses, which have important role on...
Characterization of Protein Content in Soluble Microbial Products Involved in Fouling of Membrane Bioreactor
, M.Sc. Thesis Sharif University of Technology ; Torkian, Ayoub (Supervisor) ; Mousavi, Reza (Supervisor)
Abstract
Membrane bioreactors are increasingly being used for treatment of domestic and industrial effluents. A major operational drawback of this system is membrane fouling attributed to soluble microbial products (SMPs). In this study sampling were taken from microbial products on the surface and within the membrane pores and mixed liquir for mass characterization of protein content. Water-washing was used for surface and reversible portion of pore samples. Chemical wash with urea was used for further cleansing of SMPs within the pores. All samples were concentrate by precipitation with ammonium sulfate salt prior to analysis. Total protein content of samples was measured by lowry method. SDS-PAGE...
Analysis and Improvement of Intrusion Detection Methods in Data Network Routers
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Pakravan, Mohammad Reza (Co-Advisor)
Abstract
High-quality online services demand reliable and fast packet delivery at the network layer. However, clear evidence documents the existence of compromised routers in the ISP and enterprise networks, threatening network availability and reliability. A compromised router can stealthily drop, modify, inject, or delay packets in the forwarding path to launch Denial-of-Service, surveillance, man-in-the-middle attacks, etc. So researches tried to create intrusion detection methods to identify adversarial routers and switches. To this end, data-plane fault localization (FL) aims to identify faulty links and is an effective means of achieving high network availability. FL protocols use...
Optimal Operation of a Price-Maker Virtual Power Plant in Frequency Constrained Electricity Market
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
In this thesis, optimal offering strategy problem of a virtual power plant (VPP) as a price-maker player in day-ahead frequency constrained electricity market is presented. The optimal offering strategy problem is modeled as a bi-level optimization problem. In the upper level, the total profit of VPP is maximized. In the lower level, the clearing conditions of frequency constrained electricity market is modeled. The proposed bi-level optimization problem is reformulated as a mathematical programming with equilibrium constraints (MPEC) problem by using Karush-Kuhn-Tucker (KKT) conditions. Then, the proposed MPEC problem, which is nonlinear and hard to solve by commercial solvers, is...