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Welding metallurgy of martensitic advanced high strength steels during resistance spot welding
, Article Science and Technology of Welding and Joining ; Volume 22, Issue 4 , 2017 , Pages 327-335 ; 13621718 (ISSN) ; Pouranvari, M ; Movahedi, M ; Sharif University of Technology
2017
Abstract
The paper addresses the process–microstructure–performance relationships in resistance spot welding of a martensitic advanced high strength steel. Significant softening was observed in the heat affected zone (HAZ) due to allotriomorphic ferrite formation in the inter-critical HAZ and tempering of martensite in sub-critical HAZ (SCHAZ), with the latter plays more important role in mechanical properties of the spot welds. The strain concentration associated with the HAZ softening promotes initiation of pullout failure from the soft SCHAZ. While, the peak load in the interfacial failure mode is governed by the fusion zone size, that of the pullout mode is significantly affected by the HAZ...
Investigation of Microstructure and Fracture Behavior of Similar and Dissimilar Dual Phase Steels and Martensitic Steel Spot Resistance Welding
, M.Sc. Thesis Sharif University of Technology ; Pouranvari, Majid (Supervisor) ; Movahhedi, Mojtaba (Supervisor)
Abstract
The new generation of advanced high-strength steels use in the automotive industry cause resistance spot welding study and their failure characteristics during static and dynamic loading are important. In this study, the relationship among microstructure, failure mode and mechanical properties are investigate during similar and dissimilar DP980 and MS1400 jointing advanced high-strength steels resistance spot welding. To search for micro and macro structural changes, the optical microscope, stereographic microscope and scanning electron microscope were used. Micro-hardness test, tensile shear test and Cross tension test to evaluate the mechanical properties were conducted. As well as...
Effect of Heat Treatment on the Mechanical Properties of In-situ Al-Al3Ti Nanocomposite Fabricated by Mechanical Alloying and Hot Extrusion
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
In the present work, at first Al-20 wt% Ti nanocomposite was fabricated via mechanical alloying in high energy vibratiory mill for 1-4 hours. Particles morphology, crystallite size changes and phases transformation were investigated during mechanical alloying. Next, the powders which mechanically alloyed for 2 and 4 hours was compressed by hot extrusion at 500 ℃. The extruded specimens were investigated by different tests such as density, hardness, tensile and differential scanning calorimetry (DSC). Microscopic analysis and phases transformation were also investigated by optical microscopy (OM), field emission electron microscope (FESEM) and X-ray diffraction. Then, the samples were heat...
Comprehensive structural and mechanical characterization of in-situ Al–Al3Ti nanocomposite modified by heat treatment
, Article Materials Science and Engineering A ; Volume 785 , 2020 ; Madaah Hosseini, H. R ; Azarniya, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Aluminum-Al3Ti reinforced MMCs were produced with a large amount (up to ~30 vol%) of Al3Ti phase via mechanical alloying, hot extrusion and heat treatment (as a supplementary process) of the Al–Ti elemental powder mixture, respectively. Samples in each stage were studied precise and comprehensive by field emission electron microscope, energy dispersive spectroscopy, X-ray diffraction, differential scanning calorimetry, densitometry, macro and micssro hardness, nanoindentation and tensile tests. The results indicated that after 4-h vibratory milling, the aluminum crystallite size reached 63 nm and Al3Ti phase formed in powder mixture. After hot extrusion, the volume percentage of Al3Ti...
Fabrication and Characterization of Lead-free Nanocomposite Solder Reinforced with Magnetic Coated Graphene NanoSheets (GNSs)
, Ph.D. Dissertation Sharif University of Technology ; Movahedi, Mojtaba (Supervisor) ; Kokabi, Amir Hossein (Supervisor)
Abstract
In this study, by adding graphene/cobalt reinforcement particles (CoGNSs) to lead-free low-silver SAC0307 solder, an attempt was made to improve the physical, metallurgical, and mechanical properties of the composite soft solder during the reflow soldering process. Additionally, the effect of applying a pulsed magnetic field on controlling the arrangement and distribution of graphene/cobalt particles in the solder matrix during the melting and solidification process in the reflow soldering process was evaluated. A composite solder paste was prepared by adding 0.05, 0.1, 0.2, and 0.5 wt% of graphene/cobalt particles to the lead-free low-silver SAC0307 solder powder, along with a rosin mildly...
An introduction to the next generation of radiology in the web 2.0 world
, Article IFMBE Proceedings, 30 April 2010 through 2 May 2010 ; Volume 32 IFMBE , April , 2010 , Pages 459-462 ; 16800737 (ISSN) ; 9783642149979 (ISBN) ; Malekmohammadi, M ; Youssefi, K ; Sharif University of Technology
2010
Abstract
"Web 2.0" refers to a second generation of web development and design, that facilitates communication, secure information sharing, interoperability, and collaboration on the World Wide Web. The truth is that Web 2.0 is a difficult term to define, even for web experts. Usually phrases like "the web as platform" and "architecture of participation" are used to describe this term. Examples of Web 2.0 include web-based communities, hosted services, web applications, social-networking sites, video-sharing sites, wikis, blogs, mashups and folksonomies. The Internet is changing medicine and Web 2.0 is the current buzz word in the World Wide Web dictionary. Radiology in the Web 2.0 probably refers to...
Designing a Framework for Power Exchange in Local Energy Market of a
Microgrid Using the Concept of Blockchain Technology
,
M.Sc. Thesis
Sharif University of Technology
;
Moeini Aghtaee, Moein
(Supervisor)
Abstract
By entering the concepts of transactive energy systems, microgrids and peer-to-peer networks into the local energy market, it has made it possible to implement local energy market in the microgrids more than ever. In transactive energy systems, with the elimination of the intermediate entity, exchanges take place directly between the different parts of the system, which results in increased system flexibility and reduced system costs. In this study, by applying blockchains in local energy market and in micro-grids and transactive energy systems, a framework is proposed to implement local energy market in an energy micro-grid based on blockchain. By using blockchain features and structure,...
Implication, Testing and Application of Composite Patches for Aviation Industry Structures
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
An aerial structure can be at the disposal of the owners of damage or intellectual property during its lifetime, under the supervision of static and dynamic loads and providing information in the field of recognizing temperature, humidity and environmental pressure with high-speed gradient. Capable Composite patches are used to repair damaged areas. Composite patches have unique properties such as high strength to weight ratio and corrosion resistance. In structures modified with a composite patch, various failures occur during loading, including: fiber breakage, matrix fracture, separation of fibers from the matrix or the latest patch from the main structure and failure of the metal...
Developing a New Framework for Bidding Strategy of Prosumers in Transactive Energy Markets
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaie, Moein (Supervisor)
Abstract
In this thesis, the bidding strategy of prosumers in transactive energy markets is analyzed. Considering the repaid increase in utilizing installations that convert multiple energy together, the concept of multi-carrier energy studies has been highlighted. Moreover, with the advent of district heating networks, thermal energy markets have gained much attention lately. The agent who participates in such markets can appropriately benefit from the inherent interdependencies between various energy carriers depending on their prices in different energy markets. This market player is technically called to pose an energy hub. In this regard, to deploy the inherent abilities of such an energy...
Introducing a Novel Method of Loss Allocation Based on Power Tracking in the Transactive Energy Market
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaie, Moein (Supervisor)
Abstract
The issue of loss allocation is one of the most important issues that has long been considered in electricity networks, including distribution and transmission. With changes in distribution networks over the years and the penetration of distributed energy sources, the allocation of losses has become more of a challenge than ever before. Hence, there is a need for a loss allocation algorithm that can be implemented in any network and with any topology. In this dissertation, a new, simple and at the same time efficient algorithm for allocating real losses in all networks (distribution - transmission) and with any structure (radial - circular) is presented. This algorithm first tracks the...
Developing a Framework for Reliability Studies of Distribution Energy System Comprised of Multi Energy Hubs with Heat Storages
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaie, Moein (Supervisor)
Abstract
Using energy storage systems has been remarkably improved the energy systems efficiency and reliability indicators of the system and also reduced the operating costs of these systems. Thus using them in an energy system would count as an advantage. Lately, the procedure of implementation of these systems has been studied widely and various motives behind implementing them have been reviewed. For example, the effect of cost optimization in electrical vehicles on reliability indicators from the load management perspective can be addressed. Therefore this thesis has studied the effect of electrical and thermal storage systems on the reliability indicators of an energy hub and the effect of...
Developing a New Algorithm for Detecting Electricity Theft in Crypto-Currency Miners
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaei, Moein (Supervisor)
Abstract
Cryptocurrency miners by solving complex mathematical calculations are responsible for verifying the transactions made in the blockchain network as well as maintaining its security, and as a reward for these activities, they receive bitcoins from the network. The devices used to mine cryptocurrency in order to perform the aforementioned calculations need high electricity consumption, so that the main cost of mining is related to its electricity consumption. For this reason, the ever-increasing development of the blockchain network, as well as the significant growth of the value of Bitcoin, has increased the number of cryptocurrency miners, especially in countries with low electricity costs....
Presenting a New Model for Planning Studies of a Multi-energy Microgrid to Achieve a Low-carbon Society
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaie, Moein (Supervisor)
Abstract
With the growing population and the development of human societies, the demand for energy increases. And it is expected that for the next few decades, fossil fuels will continue to be recognized as the main sources of energy supply and used to meet energy demand. One of the biggest disadvantages of fossil fuel consumption is the emission of greenhouse gases such as carbon dioxide, which raises the Earth's temperature and has devastating effects on the climate and the lives of its inhabitants. On the other hand, fossil fuels are recognized as non-renewable sources and their lifespan is only for the next few decades. Today, one of the major concerns of societies, especially in developed...
Developing a Framework for Providing the Flexibility of Active Consumers of Energy Distribution Networks
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaie, Moein (Supervisor)
Abstract
The power systems’ net-load variability and uncertainty would aggravate significantly as the penetration of Renewable Energy Resources (RERs) in power systems increases. In response, power system researchers have introduced a new concept, namely flexibility, to quantitatively and systematically deal with unavoidable features of RERs. In power distribution systems as the connection point of power systems with customers, there are many opportunities for improving the flexibility level of systems. Nowadays, the emergence of prosumers has created new opportunities for distribution system operators in providing the system with different services of flexibility in distribution systems. Therefore,...
Fault Diagnosis of Lithium-ion Battery Pack of Electric Vehicles Using Machine Learning Algorithms
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaei, Moein (Supervisor)
Abstract
In the current era, the urgent need to reduce the use of fossil fuels and limit carbon emissions has highlighted the importance of shifting from traditional gasoline-powered vehicles to electric vehicles. The evolving landscape and challenges in the field of electric vehicles highlight the importance of ensuring the safety and reliability of energy storage systems. Lithium-ion batteries play a central role in electric vehicle technology, requiring thorough research efforts. Notably, the detection of internal short circuit, a common issue in lithium-ion batteries, has become a focus of researchers in recent years. This study aims to investigate the internal short circuit fault in lithium-ion...
Developing a New Model for Energy Management System of Electric Vehicles Considering Battery Aging
, M.Sc. Thesis Sharif University of Technology ; Moeini, Moein (Supervisor)
Abstract
Today, hybrid electric vehicles are known as one of the approaches with high potential to reduce and control emissions and fossil fuel consumption in the transportation sector, so that it can be a bridge between conventional vehicles and fully electric vehicles. One of the main weaknesses and obstacles to the widespread use of these vehicles is the habit of drivers and the lack of full evolution of the technology in the battery and its management. The one of solutions to overcome this problem is structural optimization and identification of factors effecting battery health and design of energy management system considering battery health. In this thesis, an energy management system has been...
Wettability and rheological behavior of low Ag lead-free SAC/graphene and cobalt-graphene nanocomposite solder paste
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 53, Issue 8 , 2022 , Pages 2811-2822 ; 10735623 (ISSN) ; Movahedi, M ; Kokabi, A. H ; Miyashita, Y ; Azghandi Rad, S ; Sharif University of Technology
Springer
2022
Abstract
The impacts of dopant nanoparticles, graphene nanosheets (GNSs) and cobalt decorated-graphene nanosheets (CoGNSs), were studied in relation to the wettability and rheological behavior in low-Ag lead-free SAC0307 (Sn–0.3Ag–0.7Cu) solder paste. The solidification range of the solders was evaluated using differential scanning calorimetry. Phase identification in the solder bulk and interface of the solder and copper substrate was carried out by X-ray diffraction and energy-dispersive X-ray spectroscopy. Spreading properties and reactive wetting behavior along with the rheological properties of the solders were also studied. Results showed that the addition of both nanoparticles did not...
An alternative additive manufacturing-based joining method to make Metal/Polymer hybrid structures
, Article Journal of Manufacturing Processes ; Volume 45 , 2019 , Pages 217-226 ; 15266125 (ISSN) ; Movahedi, M ; Tamizi, M ; Tartifzadeh, Z ; Alipour, S ; https://www.sciencedirect.com/science/article/abs/pii/S1526612519302087
Elsevier Ltd
2019
Abstract
Fused Deposition Modeling with Polypropylene filament was employed to make a lap joint between Polypropylene and pre-punched Al-Mg alloy sheets, in the form of bonds between the polymeric substrate and the additive part and mechanical lock between the additive part and aluminum base sheet. Effects of the joint interface area (hole diameter of 5–13 mm) and preheating of the substrates (room temperature, 50 and 90℃) were investigated on the mechanical properties of the joints. Peak load in the tensile-shear and cross-tension tests increased with enhancement of the joint interface area (up to ˜280 N and ˜160 N, respectively). Higher joint strength in the tensile-shear test compared to the...
Developing an Efficient Framework for Involving Degradation Model of Lithium-ion Battery in Optimization Studies of a Residential Energy Hub
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaie, Moein (Supervisor)
Abstract
Energy storage systems are expected to play an important role in future renewable-based power systems. Recently, lithium-ion batteries have been attracting considerable attention as alternative energy storage systems due to their advantages. In this study, viability of battery storage systems as large-scale energy storage systems is studied in the context of a residential energy hub. A stochastic optimization problem is proposed for energy management of the energy hub where wind generation and demand are considered uncertain. In order to account for the degradation costs of the battery storage system, a data-driven State-of-health prediction model is developed based on the relevance vector...
Developing a New Model to Estimate Flexibility of Thermal and Electrical Storage Units in Active Energy Distribution Systems
, M.Sc. Thesis Sharif University of Technology ; Moeini Aghtaie, Moein (Supervisor)
Abstract
Nowadays, variable generation and renewable energy resources are increasingly penetrating the energy systems to supply the users' demand at the distribution grid. Variable Energy Resources (VER) can provide energy at a lower cost, and they also guarantee cleaner energy. Still, the uncertainty and variability from these resources' output can affect the net-load of the system at each hour. Besides, the issue of energy balance has always been a challenge for the energy distribution networks. A comprehensive way to unravel this problem is to use flexible resources. One of the crucial issues in the flexibility debate is meeting this need by different energy resources. It is always an issue for...