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    Fabrication of Thin Layers Semiconductor Based on CTS

    , M.Sc. Thesis Sharif University of Technology Jalali Chamani, Hesam (Author) ; Mahdavi, Mohammad (Supervisor)
    Abstract
    Copper-based semiconductors have received a great deal of attention due to their high absorption coefficient, direct and adjustable energy gap with stoichiometry, low frequency and toxicity. Multicomponent nanocrystals such as CuInS2, Cu (In, Ga) (S, Se) 2, Cu2ZnSnS4 and Cu2SnS3 (CTS) have been successfully synthesized by colloidal synthesis and have shown application potentials such as energy conversion, photocatalyst, thermoelectric and biomedical. Among these, the CTS ternary semiconductor with p-type conduction is one of the most well-known compounds of group I-IV-VI, which consists of abundant and non-toxic elements. In this research, thin-film solar cells with FTO / TiO2 / In2S3 / CdS... 

    Investigation of Wear Properties of Nanocrystalline through Multiscale Modeling of Nanoindentation and Nanoscratch Test

    , Ph.D. Dissertation Sharif University of Technology Chamani, Mohammad (Author) ; Farrahi, Gholamhossein (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
    Abstract
    Nanocrystalline materials have received increasing attention during the last decades. Polycrystalline structures with grain sizes less than 100 nm are referred as nanocrystalline (NC). Their mechanical properties differ significantly from polycrystalline structures. As an example, hardness and wear resistance of nanocrystalline structures are higher than those of polycrystalline structures. With the reduction of grain size, hardness increases based on the Hall–Petch relation. However, at the very small grain sizes the Hall–Petch relation breaks down and a fundamental shift takes place in hardening mechanism. Molecular dynamics (MD) simulation offers a powerful method for the investigation of... 

    Effect of Initial Surface Roughness on the Residual Stress Profile Induced by Shot Peening Process using Finite Element Method and Machine Learning Algorithms

    , M.Sc. Thesis Sharif University of Technology Nazemi Azad, Farbod (Author) ; Farrahi, Gholamhossein (Supervisor) ; Chamani, Mohammad (Co-Supervisor)
    Abstract
    Shot peening process, which induces compressive residual stress near the surface, is one of the most effective methods for enhancing surface properties. Shot peening on smooth surfaces increases surface roughness, which is a factor that can reduce fatigue life. Conversely, the distribution of compressive residual stress contributes to improved fatigue life. Therefore, examining the initial surface conditions and the effects of average surface roughness on residual stress distribution is essential.In this study, due to the limited attention given to initial surface roughness in previous research, a finite element model of the shot peening process was developed considering the actual... 

    Dye Removal from Wastewater Using Functionalized Copper Oxide–zinc Oxide Nanocomposite as an Adsorbent

    , M.Sc. Thesis Sharif University of Technology Chamani, Houman (Author) ; Kariminia, Hamid Reza (Supervisor) ; Mahmoudi, Niyaz Mohammad (Supervisor)
    Abstract
    In this thesis, the copper oxide - zinc oxide nanocomposite was synthesized and functionalized using 3-aminopropyltrimethoxysilane. The functionalized nanocomposite was characterized using X-ray Diffraction spectroscopy (XRD), Fourier Transform Infrared (FT-IR), X-ray Fluorescence Spectroscopy (XRF), Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET). Dye removal from synthetic wastewater was done in a batch system using functionalized copper oxide - zinc oxide nanocomposite as adsorbent. Direct red 23, direct red 80 and direct red 81 were used for preparation of synthetic wastewaters. The effects of operational parameters such as adsorbent dosage, initial dye concentration,... 

    Residual Stress Determination of Multi-pass Welding Process, Stress Relieving Procedures and Its Effect on Crack Propagation

    , M.Sc. Thesis Sharif University of Technology Chamani, Mohammad (Author) ; Farahi, Gholamhossein (Supervisor)
    Abstract
    One of the most important issues in welding is residual stresses. It is desirable to produce less residual stresses when possible and to reduce them which remain in the structure. At the present, various methods have been developed to reduce the residual stresses. The most important methods are heat treatment, shot peening, and grinding. The main problem in using these methods is cost, and for large structures these methods are often impractical. In recent decades, a technique called vibratory stress relief has been developed. It is used for large structures without limitation of size and weight; besides, the cost of this process is much less in comparison with other conventional methods... 

    Localization Optimization: A Customized Cuckoo approach on DV-Hop Algorithm

    , M.Sc. Thesis Sharif University of Technology Chamani Tabriz, Solmaz (Author) ; Hemmatyar, Ali Mohammad Afshin (Supervisor) ; Mazinani, Majid (Supervisor)
    Abstract
    Node localization is an important issue in dynamic environments for location-dependent applications of Wireless Sensor Networks (WSNs). Geographical location information is necessary in many WSN applications. The goal of localization algorithm is to assign geographical coordinates to each unknown node position. Among different localization algorithms, DV-hop is one of the well- known algorithms. DV-hop algorithm is a range-free algorithm and has significant error in node location estimation. Since the node deployment is stochastic, minimizing this error has a critical role in location estimation accuracy of the algorithm. Increasing communication radius and number of anchors, to the certain... 

    Toward a Method for Citation Recommendation in Citation Network

    , M.Sc. Thesis Sharif University of Technology Ghareh Chamani, Javad (Author) ; Habibi, Jafar (Supervisor)
    Abstract
    Study of real networks has become an important research task. Real networks appear in different domains such as social networks and biological networks. It is also possible to extract various networks from the set of scientific collaborations of published papers. In this project we investigate the analysis of citation network and co-authorship networks of scientific papers in order to find out a new method in citation recommendation of scientific papers. Presented method have some superior properties over existing citation recommendation systems like combining different fields for suggesting most relevant papers to user, in response of user’s input keywords. For presenting this method we... 

    A Five-Component Reaction for the Synthesis of New Benzylidenemalononitrile Derivatives Using Ultrasound Irradiation

    , M.Sc. Thesis Sharif University of Technology Chamani, Fatemeh (Author) ; Matloubi Moghaddam, Firouz (Supervisor)
    Abstract
    Nowadays, using one-pot multicomponent reactions in the synthesis of organic and natural compounds has attracted a lot of attention due to their ideal synthetic features. These types of reactions play an important role in synthetic chemistry by reducing reaction steps, costs, wastes, and by-products and increasing the reaction efficiency as an efficient method. The issue that led to this project was the development of a novel procedure for developing synthetic methods for the synthesis of thioxo-pyrrolidine 3-carbutamide compounds. In this study, the first Mumm rearrangement was performed by using dithiocarbamates by applying ultrasonic irradiation. The reaction was investigated in methanol... 

    Encryption Aware Query Processing for Data Outsourcing

    , Ph.D. Dissertation Sharif University of Technology Ghareh Chamani, Javad (Author) ; Jalili, Rasool (Supervisor)
    Abstract
    Data outsourcing provides cost-saving and availability guarantees. However, privacy and confidentiality issues, disappoint owners from outsourcing their data. Although solutions such as CryptDB and SDB tried to provide secure and practical systems, their enforced limitations, made them useless in practice. Inability in search on encrypted data, is one of the most important existing challenges in such systems. Furthermore, the overhead of mechanisms such as FHEs, removes them from considering for any practical system. Indeed, special purpose encryptions would be the only usable mechanisms for such purposes. However, their limited functionality does not support some important required... 

    Effect of microstructure on crack behavior in nanocrystalline nickel using molecular dynamics simulation

    , Article Theoretical and Applied Fracture Mechanics ; Volume 104 , 2019 ; 01678442 (ISSN) Moradi, M ; Farrahi, G. H ; Chamani, M ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    The crack growth process in columnar nanocrystalline samples is simulated using the molecular dynamics method. The effects of grain size, grain boundary, crystallographic orientation and crack tip position on the crack growth behavior are investigated. Different sets of samples with mean grain sizes ranging from 4 nm to 14 nm are prepared. Samples with a similar number of grains and identical dimensions are considered for examining the impact of grain boundary and crystallographic orientation. To assess the effect of the grain boundary, no constraint is considered on the position and orientation of grains, while only the grain orientations are changed to examine the effect of... 

    Molecular dynamics simulation of nanoindentation of nanocrystalline Al/Ni multilayers

    , Article Computational Materials Science ; Volume 112 , 2016 , Pages 175-184 ; 09270256 (ISSN) Chamani, M ; Farrahi, G. H ; Movahhedy, M. R ; Sharif University of Technology
    Elsevier  2016
    Abstract
    Molecular dynamics simulations are employed to investigate material properties of nanocrystalline aluminum and nanocrystalline Al/Ni multilayers at low temperature. For this purpose, both single crystal and nanocrystalline multilayers with different grain sizes and grain morphology are used as the substrate. The results of the simulations show that hardness and elastic modulus decrease with refinement of grain size in nanocrystalline aluminum and refinement of grain size and layer thickness in nanocrystalline Al/Ni multilayers, regardless of grain morphology. Furthermore, the angle between two adjacent grains, which is directly connected to the grain boundary thickness, has a great influence... 

    Friction behavior of nanocrystalline nickel near the Hall-Petch breakdown

    , Article Tribology International ; Volume 107 , Volume 107 , 2017 , Pages 18-24 ; 0301679X (ISSN) Chamani, M ; Farrahi, G. H ; Movahhedy, M. R ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    Large-scale molecular dynamics simulations are carried out to investigate the friction behavior of nanocrystalline nickel (Ni) at low temperature. Grain sizes ranging from 4–11 nm are used to explore the behavior of nanocrystalline Ni near the Hall-Petch breakdown. Effects of grain size, grain morphology and scratch depth on coefficient of friction (COF) and deformation mechanism of nanocrystalline Ni are investigated. Reduction of the COF with the refinement of grain size in nanocrystalline nickel is observed, however, for a grain size of 5 nm this trend is observed to be reversed. It is also found that scratch depth can influence the estimation of friction behavior of nanocrystalline... 

    Effect of residual stress on failure of tube-to-tubesheet weld in heat exchangers

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 32, Issue 1 , 2019 , Pages 112-120 ; 17281431 (ISSN) Farrahi, G. H ; Minaii, K ; Chamani, M ; Mahmoudi, A. H ; Sharif University of Technology
    Materials and Energy Research Center  2019
    Abstract
    In a shell and tube heat exchanger, the failure of tube-to-tubesheet welds results in high-pressure water jet which erodes the refractory in front of the tubesheet. Finite element method was employed to simulate the welding process and post weld heat treatment (PWHT) to find the factors affecting the failure in tube-to-tubesheet weldments. Residual stresses in two different geometries of tube-to-tubesheet weldment were calculated through uncoupled thermal-structural analysis. The results showed that the values of residual stresses are higher in heat exchanger of site 1 than site 2 due to more weld passes and geometry of connection. Also, the maximum stress in site 1 occurs at the shellside... 

    A new Mumm-type rearrangement with dithiocarbamates via isocyanide-based multicomponent reaction under ultrasound irradiation: synthesis of polysubstituted pyrrolidine compounds

    , Article New Journal of Chemistry ; Volume 44, Issue 23 , May , 2020 , Pages 9699-9702 Matloubi Moghaddam, F ; Goudarzi, M ; Chamani, F ; Mohammadzadeh Dezag, H ; Sharif University of Technology
    Royal Society of Chemistry  2020
    Abstract
    A novel and efficient multicomponent reaction for the synthesis of polysubstituted pyrrolidine derivatives is described under catalyst-free conditions using ultrasonic irradiation. The reactions were performed via a one-pot four-component condensation of secondary amines, carbon disulfide, isocyanides, and gem-dicyano olefins at room temperature to afford polysubstituted pyrrolidines diastereoselectively in 56-96% yields. This is the first report of a Mumm-type rearrangement with dithiocarbamates followed by intramolecular cyclization, which leads to the preparation of the key structure of pyrrolidine. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche... 

    Effect of residual stress on failure of tube-to-tubesheet weld in heat exchangers

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 32, Issue 1 , 2019 , Pages 112-120 ; 17281431 (ISSN) Farrahi, G. H ; Minaii, K ; Chamani, M ; Mahmoudi, A. H ; Sharif University of Technology
    Materials and Energy Research Center  2019
    Abstract
    In a shell and tube heat exchanger, the failure of tube-to-tubesheet welds results in high-pressure water jet which erodes the refractory in front of the tubesheet. Finite element method was employed to simulate the welding process and post weld heat treatment (PWHT) to find the factors affecting the failure in tube-to-tubesheet weldments. Residual stresses in two different geometries of tube-to-tubesheet weldment were calculated through uncoupled thermal-structural analysis. The results showed that the values of residual stresses are higher in heat exchanger of site 1 than site 2 due to more weld passes and geometry of connection. Also, the maximum stress in site 1 occurs at the shellside... 

    Multi-User Dynamic Searchable Symmetric Encryption With Corrupted Participants

    , Article IEEE Transactions on Dependable and Secure Computing ; Volume 20, Issue 1 , 2023 , Pages 114-130 ; 15455971 (ISSN) Ghareh Chamani, J ; Wang, Y ; Papadopoulos, D ; Zhang, M ; Jalili, R ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2023
    Abstract
    We study the problem of multi-user dynamic searchable symmetric encryption (DMUSSE) where a data owner stores its encrypted documents on an untrusted remote server and wishes to selectively allow multiple users to access them by issuing keyword search queries. Specifically, we consider the case where some of the users may be corrupted and colluding with the server to extract additional information about the dataset (beyond what they have access to). We provide the first formal security definition for the dynamic setting as well as forward and backward privacy definitions. We then propose μSE, the first provably secure DMUSSE scheme and instantiate it in two versions, one based on oblivious... 

    GraphOS: Towards Oblivious Graph Processing

    , Article Proceedings of the VLDB Endowment ; Volume 16, Issue 13 , 2023 , Pages 4324-4338 ; 21508097 (ISSN) Chamani, J. G ; Demertzis, I ; Papadopoulos, D ; Papamanthou, C ; Jalili, R ; Koutrika G ; Yang J ; Sharif University of Technology
    VLDB Endowment  2023
    Abstract
    We propose GraphOS, a system that allows a client that owns a graph database to outsource it to an untrusted server for storage and querying. It relies on doubly-oblivious primitives and trusted hardware to achieve a very strong privacy and efficiency notion which we call oblivious graph processing: the server learns nothing besides the number of graph vertexes and edges, and for each query its type and response size. At a technical level, GraphOS stores the graph on a doubly-oblivious data structure, so that all vertex/edge accesses are indistinguishable. For this purpose, we propose Omix++, a novel doubly-oblivious map that outperforms the previous state of the art by up to 34×, and may be... 

    Comparison between two different hemichromes of hemoglobins (HbA and HbS) induced by n-dodecyl trimethylammonium bromide: Chemometric study

    , Article Colloids and Surfaces B: Biointerfaces ; Volume 63, Issue 2 , 2008 , Pages 183-191 ; 09277765 (ISSN) Mojtahedi, M ; Parastar, H ; Jalali Heravi, M ; Chamani, J ; Chilaka, F. C ; Moosavi Movahedi, A. A ; Sharif University of Technology
    2008
    Abstract
    The interaction of n-dodecyl trimethylammonium bromide (DTAB) with oxyhemoglobin A and oxyhemoglobin S is investigated using UV-visible absorption spectra and chemometric resolution techniques. Oxyhemoglobins (A and S) induced to partial oxidized form (ferrihemoglobin) by DTAB and finally transform to fully oxidized hemichrome. Hemichrome mole fractions of HbS are more than HbA because of more hydrophobic interaction of DTAB-HbS in second set of binding site relative to DTAB-HbA. The visible spectra between 500 and 650 nm are used for identifying the present components in solution because each species of hemoglobin has a specific spectrum in this region. The number of components and mole... 

    Construction of an Experimental Device for Foaming Agent and an Experimental Study of the Properties of Foaming Agent

    , M.Sc. Thesis Sharif University of Technology Mohammad Karami (Author) ; Bazargan, Mohammad (Supervisor)
    Abstract
    The primary purpose of acidizing operations in the oil and gas industry is to enhance hydrocarbon production. Acidizing has been a common and conventional method for years, especially when production engineers face issues like declining reservoir pressure leading to reduced production rates. Initially, the treatment solution is referred to as matrix acidizing. In acidizing operations, different additives are combined with the acid to control its behavior in the reservoir. These additives may include iron control agents, corrosion inhibitors, friction reducers, and more. Incompatibility among these additives, the acid, and reservoir fluids can lead to severe damage to the reservoir.... 

    Numerical Analysis of An Annular Gas Turbine Combustor

    , M.Sc. Thesis Sharif University of Technology Gandomi, Mohammad Hossein (Author) ; Farshchi, Mohammad (Supervisor)
    Abstract
    The goal of this research is the simulation of the annular combustion chamber of the turbine engine utilized by liquid fuel. The achievement to this goal will lead to create numerical tools for parametric study, analysis and combustion chamber designing.For this reason simple geometry has been considered. This simplicity of geometry causes to facilitate in parametric study and decrease in saving time for modeling and meshing. This combustion chamber is a simplified model of engine CF6. In recent study, the k – ε realizable model has been used for turbulence modeling. For non-adiabatic condition, chemical reaction is dissolved by utilizing probability density function along with laminar...