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On the solution treatment of severely deformed AA2024-O and subsequent natural aging
, Article Journal of Materials Research and Technology ; Volume 20 , 2022 , Pages 1558-1569 ; 22387854 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Elsevier Editora Ltda
2022
Abstract
In this research, the effect of applying severe strain before solid solution treatment (SST) for AA2024-O was studied. Providing concurrent insights into solutionizing behavior and microstructural evolution corresponding to hardness is important. Multi-directional forging (MDF) was used as a severe plastic deformation (SPD) method. After applying SST on MDFed (4 passes) and as-annealed samples, natural aging (NA) was used as the following treatment to examine the role of severe strain on the solutionizing behavior. In most previous attempts, SPD has been used after SST, but one of the innovations of the present work is the study of SPD before SST. Experimental results show that adding a...
On The Solution Treatment of Severely Deformed AA 2024-O and its Post-Severe Plastic Deformation
, M.Sc. Thesis Sharif University of Technology ; Kazeminezhad, Mohsen (Supervisor)
Abstract
In this study, the solution treatment of severely deformed AA 2024-O and its post-severe plastic deformation is investigated. The investigation was performed in two cases of pre-multi directional forging (pre-MDF) and post-multi directional forging (post-MDF) on the solution treatment. After applying pre-MDF, finding kinetics of temperature and solution time caused that natural aging to be studied as a treatment after solid solution. By measuring the difference in hardness before and after natural aging in pre-MDFed and un-MDFed samples, 500℃ and 5 minutes were found to be the most desirable temperature and time in terms of mechanical properties and microstructure. Continuous...
Secure transmission with covert requirement in untrusted relaying networks
, Article 9th International Symposium on Telecommunication, IST 2018, 17 December 2018 through 19 December 2018 ; 2019 , Pages 670-675 ; 9781538682746 (ISBN) ; Azmi, P ; Kuhestani, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we investigate the problem of secure communication with covert requirement in untrusted relaying networks. Our considered system model contains one source, one destination, one untrusted relay, and one Willie. The untrusted relay tries to extract the information signal, while the goal of Willie is to detect the presence of the information signal transmitted by the source, in the current time slot. To overcome these two attacks, it is assumed that the destination and the source inject jamming signal to the network in phase I and phase II, respectively. Accordingly, the communication in our proposed system model is accomplished in two phases. In the first phase, when the source...
Does the short-term boost of renewable energies guarantee their stable long-term growth? Assessment of the dynamics of feed-in tariff policy
, Article Renewable Energy ; Volume 159 , October , 2020 , Pages 1252-1268 ; Hamed Shakouri, G ; Mashayekhi, A. N ; Kazemi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Feed-in tariff (FiT) is one of the most efficient ways that many governments throughout the world use to stimulate investment in renewable energies (REs) technology. For governments, financial management of the policy could be challenging as it needs a considerable amount of budget to support RE producers during the long remuneration period. In this paper, it has been illuminated that the early growth of REs capacity could be a temporary boost. And the socio-economic structure of the system will backlash the policy if some social mechanisms are not considered. Social tolerance for paying REs tax and potential investors’ trust emanated from budget-related mechanisms -which have rarely been...
The Biological Removal of Methane of Contaminated Air
, M.Sc. Thesis Sharif University of Technology ; Shaygan Salek, Jalaloddin (Supervisor) ; Rashtchian, Davood (Co-Advisor)
Abstract
Trash production in Iran is increasing. The majority of trash is being buried and that induces the emission of methane gas (CH4), which is a greenhouse gas. In this thesis, the aim was mostly to remove methane from greenhouse gases by applying several cheap and abundant substances. For this purpose, a biofilteration system was provided. It has been tested using two packings: straw and plastic. To provide the necessary materials for bacterium growth, a nutrient solution was used. The results of this work have revealed that plastic proved to be more effective than another substance and the removal percent obtained was about 61%. The result for straw was 42%. Furthermore, the experiments were...