Thermal buckling analysis of piezoelectric functionally graded plates with temperature-dependent properties

, Article Mechanics of Advanced Materials and Structures ; Volume 22, Issue 10 , Nov , 2015 , Pages 864-875 ; 15376494 (ISSN) Yaghoobi, H ; Fereidoon, A ; Khaksari Nouri, M ; Mareishi, S ; Sharif University of Technology

Taylor and Francis Inc 2015

Abstract

In this study, the thermal buckling analysis of hybrid laminated plates made of two-layered functionally graded materials (FGMs) that are integrated with surface-bonded piezoelectric actuators referred to as (P/FGM)s are investigated. Material properties for both substrate FGM layers and piezoelectric layers are temperature-dependent. Uniform temperature rise as a thermal load and constant applied actuator voltage are considered for this analysis. By definition of four new analytic functions, the five coupled governing stability equations, which are derived based on the first-order shear deformation plate theory, are converted into fourth-order and second-order decoupled partial differential...

An Investigation on Microstructure and Mechanical Properties of TLP Bonded Al/SiC Composite Using Powder Technique

, M.Sc. Thesis Sharif University of Technology Khaksari Noori, Mohammad (Author) ; Ekrami, A.A (Supervisor) ; Bagheri, REZA (Supervisor)

Abstract

In this research Al6061-SiC composite bonding was done by transient liquid phase method using powder copper intermediate layer. In the first stage feasibility of making this junction in ambient condition was studied. In order to find process optimum temperature, experiments were performed in 560°C, 570°C, 580°C and 590°C for 2 hours. Optical microscopy, scanning electron microscopy and EDS analysis were utilized for this study. Moreover, shear strength determination test was done to assess and compare mechanical properties and also to determine the optimum bonding temperature.
In second stage, base composite and bonded specimens were homogenized in 530°C for 5 and 10 hours. Effect of...

Modification of Surface Nanostructure and Mechanical Properties by Friction Stir Processing in Al 5083 with Al2O3 and Cu Particles

, M.Sc. Thesis Sharif University of Technology Khaksari, Mehdi (Author) ; Kokabi, Amir Hossein (Supervisor) ; Akbarzadeh Changiz, Abbas (Supervisor)

Abstract

Al 5083 is a non-heat treatable alloy that widely used in the aerospace and automotive industry due to its low density and high strength. However, poor wearing behavior and low elastic modulus restrict its engineering applications. Metal matrix composites (MMCs) have advantages of high strength and modulus by reinforcement of second phase. Also, MMCs have excellent dimensional stability, damping capacity and wear, creep and fatigue resistances as compared with the corresponding monolithic alloys. Vast loss in ductility and toughness occurs by non- deformable ceramic reinforcements. For the surface engineering purposes, ceramic particles are added in the surface layers of components, whereas...

, M.Sc. Thesis Sharif University of Technology Mardiha, Milad (Author) ; Vakilian, Mehdi (Supervisor) ; Fardmanesh, Mehdi (Supervisor)

Design and Fabrication of Inductive High Temperature Superconducting Fault Current Limiter

, Ph.D. Dissertation Sharif University of Technology Hekmati, Arsalan (Author) ; Vakilian, Mehdi (Supervisor) ; Fardmanesh, Mehdi (Supervisor)

Abstract

The continuous rise in electricity demand and the ever growing power generation in different power networks over the world have caused the short circuit level in the power systems to exceed the operational rating of the installed power devices (including cables, circuit breakers and buses). Replacing these devices with new higher rating devices is an expensive solution. From this point of view, utilizing fault current limiters is an economical solution. Superconducting fault current limiters form an efficient category of current limiters. This type is expected to be studied and used widely in future due to their advantages. In this thesis, the first chapter reviews the superconductivity...

Enhancement of THz Radiation from Josephson Junctions in Superconductors Using Electromagnetic Resonators

, M.Sc. Thesis Sharif University of Technology Iranmehr, Masoud (Author) ; Ahmadi Boroujeni, Mehdi (Supervisor) ; Fardmanesh, Mehdi (Supervisor)

Abstract

Terahertz waves which includes frequencies between 100 GHz to 10 THz of electromagnetic spectrum have found many applications in science, medical treatments and industry. One of the recent methods to produce these waves is using nonlinear properties of superconductors based on Josephson junctions which inherently appear in some superconductors called BSCCO. Stack of intrinsic junctions of these superconducting materials can radiate terahertz waves by only applying a DC voltage across them. This Thesis investigates some of these structures based on Josephson junctions to produce coherent radiation of terahertz waves. For the optimization of the radiation power, this study also investigates...

On the Spectrum of Modified Theories of Gravity

, M.Sc. Thesis Sharif University of Technology Seraj, Ali (Author) ; Golshani, Mehdi (Supervisor) ; Sheikh Jabbari, Mohammad Mehdi (Supervisor)

Abstract

There are different approaches in modifications of General Relativity as the theory of gravity. The modified theories of gravity are important cases in this context, which mostly start by modifying the Einstein-Hilbert action, while keeping the general covariance. Within the modified theories of gravity, we consider two cases. The first is the f(R) theories of gravity, and the second is curvature squared theories of gravity with an action like S = ∫d4x pg( 116GR + (R)2 + R2 +(R)2). Curvature squared theories of gravity have interesting feautures, most important of which is renormalizability, in contrast with General Relativity. But this advantage, as noted by K.S. Stelle in 1977 comes at...

Critique and Survey of Various Formulation of Multiverse Theory

, Ph.D. Dissertation Sharif University of Technology Masoumi, Saeed (Author) ; Golshani, Mehdi (Supervisor) ; Sheikh Jabbari, Mohammad Mehdi (Supervisor)

Abstract

Multiverse scenario has been recently addressed by physicists and they have found it useful in many areas of physics. In this dissertation, I have treated some issues about multiverse such as the kinds of multiverses, the arguments for or against multiverse, areas in which multiverse is introduced, etc. This dissertation has six chapters and an appendix. In the chapter one, some classifications of multiverse is introduced, and also some definitions of the concept of a world is presented. Then, my classification and definition of a multiverse and a world is introduced. In the chapter two, the concept of possible worlds in philosophy and its relationship with multiverse hypothesis is examined....

On Thermodynamics and Phase Space of Near Horizon Extremal Geometries

, Ph.D. Dissertation Sharif University of Technology Hajian, Kamal (Author) ; Sheikh-Jabbari, Mohammad Mehdi (Supervisor) ; Golshani, Mehdi (Co-Advisor)

Abstract

Near Horizon Extremal Geometries (NHEG), are geometries which may appear in the near horizon region of the extremal black holes. These geometries have SL(2;R)U(1)n isometry, and constitute a family of solutions to the theory under consideration. In the first part of this report,their thermodynamic properties are reviewed, and their three universal laws are derived. In addition, at the end of the first part, the role of these laws in black hole thermodynamics is presented. In the second part of this thesis, we review building their classical phase space in the Einstein-Hilbert theory. The elements in the NHEG phase space manifold are built by appropriately chosen coordinate transformations of...

Optimal Multicriteria Design of HTS Transformer and Construction of a Laboratory Scale Sample

, Ph.D. Dissertation Sharif University of Technology Moradnouri, Ahmad (Author) ; Vakilian, Mehdi (Supervisor) ; Fardmanesh, Mehdi (Co-Supervisor) ; Hekmati, Arsalan (Co-Supervisor)

Abstract

Employing high-temperature superconducting (HTS) tapes, instead of copper or aluminum wires for winding in a superconducting transformer, results in a series of significant advantages; such as: smaller volume, lighter weight, higher efficieny, greatly extended overload capability, better voltage regulation, lower life cycle cost, fault current limiting capability, lower environmental pollution and lower risk potential against fire hazards.In this thesis, optimal design of flux diverter using genetic algorithm for axial short circuit force reduction in HTS transformers has been performed. Then, multilayered flux diverters have been proposed for reduction of weight and losses. The impact of...

A Multi-Objective Robust Optimization Model for Logistics Planning in the Earthquake Response Phase [electronic resource]

, Article Transportation Research Part E: Logistics and Transportation Review, Elsevier ; Volume 49, Issue 1, January 2013, , Pages 217–249 Najafi, M. (Mehdi) ; Eshghi, Kourosh ; Dullaert, Wout ; Sharif University of Technology

Abstract

Usually, resources are short in supply when earthquakes occur. In such emergency situations, disaster relief organizations must use these scarce resources efficiently to achieve the best possible emergency relief. This paper therefore proposes a multi-objective, multi-mode, multi-commodity, and multi-period stochastic model to manage the logistics of both commodities and injured people in the earthquake response. Also, a robust approach is developed and used to make sure that the distribution plan performs well under the various situations that can follow an earthquake. Afterwards, it proposes a solution methodology according to hierarchical objective functions and uses it to illustrate the...

Monitoring of Valve Leakage in Internal Combustion Engine Using Acoustic Emission Method

, Ph.D. Dissertation Sharif University of Technology Jafari, Mohammad (Author) ; Behzad, Mehdi (Supervisor) ; Mehdigholi, Hamid (Supervisor) ; Ahmadi, Mohammad Mehdi (Co-Advisor)

Abstract

Valve leak detection is very important due to bad direct effects on parts life and engine power. Acoustic emission (AE) has a good known ability on leak detection between fault detection methods. The aim of this thesis is presenting the ability of AE method for valve leak detection in internal combustion engines. The research method in a general framework based on the idea that firstly some evaluations were done in static tests for leakage due to three faults including clearance, quasi-crack and notch. Then, the evaluations were continued with dynamic analysis of rotational speeds and different loads on the engine. Finally, the neural network approach was used to automatically detect all...

Distributed Generation Planning in Deregulated Electric Industry Using Multi-objective Optimization

, M.Sc. Thesis Sharif University of Technology Ahmadi, Mohammad (Author) ; Ehsan, Mehdi (Supervisor)

Ground Water Denitrification by Packed Bed Bioreactor With KMT Packing

, M.Sc. Thesis Sharif University of Technology Hemmati, Azadeh (Author) ; Borghei, Mehdi (Supervisor)

Abstract

In this study biological denitrification method by moving bed biofilm reactor is investigated. The main advantage of MBBR reactor is due to their capacity for high removal rates and low operational problems such as clogging. Two MBBRs in series with 3 liter volume each, were designed in experimental set up and used in this research. Nitrification reactor worked under aerobic conditions and denitrification reactor operated under anaerobic conditions. Methanol was used as carbon source in the reactors throughout the study. Fifty percent of each reactor volume was occupied with KMT1 packing. To finding the optimum nitrate loading rate, the concentration of ammonium and nitrate were changed from...

Operation Planning in Restructured Power System Integrating Wind /Solar Energy

, Ph.D. Dissertation Sharif University of Technology Siahkali, Hassan (Author) ; Vakilian, Mehdi (Supervisor)

Abstract

In power system operation, the term "operation planning" carries a wide range of meaning. For some utilities, operation planning denotes primarily short-term planning tasks (up to several days), such as load forecasting, unit commitment, hydro-thermal coordination, transaction pricing, fuel allocation, and security analysis while for other companies operational planning is interpreted in a wider context, and include mid-term planning activities (up to several months), such as maintenance planning, fuel budgeting, rate forecasting, network planning, relay coordination, etc. The mid-term planning provides the link between the long-term and short-term planning programs. The duration of this...

Passive Worm and Malware Detection in Peer-to-Peer Networks

, M.Sc. Thesis Sharif University of Technology Fahimian, Sahar (Author) ; Kharrazi, Mehdi (Supervisor)

Abstract

Due to advantages of Peer-to-Peer (P2P) networks, many internet users use them for content distribution (Many internet users distribute content using them). These systems may be categorized to Centralized, Pure, and Hybrid. Gnutella is a heavily decentralized and unstructured file sharing P2P networks that are responsible for a good part of the traffic on the internet. These P2P networks are at risk of many security threats from internet worms. Internet worms and their threats are a major concern to the networking community. In this thesis we concentrate on passive non-scanning worms and propose a novel approach to detect such worms. As part of our work, we collected data from the Gnutella...

Optimization of Oily and Biological Sludge Digestion and Dewatering Process for Arak Refinery Wastewater Treatment Plant

, M.Sc. Thesis Sharif University of Technology Jalouli, Alireza (Author) ; Borghei, Mehdi (Supervisor)

Abstract

Different strategies for the treatment and disposal of petroleum and biological sludge found in the treatment and reuse unit of Arak Petroleum Refinery have been studied in the present study. To this end, the resources found in the literature corresponding to the different fields of sludge treatment were studied and a summary of them which was required by this research was mentioned in the thesis. Considering the problems bound to the wastewater treatment unit of this refinery plant and the previous studies, two completely separate strategies were devised. The first one concerns petroleum and biological sludge being produced continuously. The method of aerobic fixation of petroleum sludge by...

Modeling of HV Substation Automation Systems and Evaluating of Operation Failure

, M.Sc. Thesis Sharif University of Technology Falahati, Bamdad (Author) ; Vakilian, Mehdi (Supervisor)

Abstract

In two past decades, a revolution has occurred by emerging of substation automation system in field of substation control and protection system. The traditional control system has changed to the modern automation systems which are based on computer networks. The development of this project become possible by having experience in and being familiar with automation systems, studying equipment specifications, tasks, and criteria and analyzing operation of various systems. The main target of this thesis is evaluating the automation system precisely and exhaustively and developing a model based on mathematical relations. This model is founded based on the application and analysis of the networks....

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...

Relative Merits of the Two Famous Formulations of Bohmian Mechanics

, Ph.D. Dissertation Sharif University of Technology Atiq, Mahdi (Author) ; Golshani, Mehdi (Supervisor)

Abstract

The goal of this thesis is to evaluate the strengths and weaknesses of the two existing formulations of Bohmian mechanics. The first one was proposed by Bohm, and emphasizes on the dynamics being second-order, and in which, the key tool for explaining the quantum phenomena is a non-classical potential, called "the quantum potential". In this approach, the postulates of de Broglie's "pilot-wave" theory, which now is known as Bohmian mechanics, are non-fundamental and are special to the atomic level. The possibility is proposed that these postulates become subjected to some modifications at the nuclear or lower levels, but no particular way for performing such modifications is suggested. The...