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heidari-aliabadi---mojtaba
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Design of a Barge Equipped with Turbojet for oil well Fire Extinguishing
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehrani fard, Majid (Supervisor) ; Mehdigholi, Hamid (Supervisor)
Abstract
In this thesis, the use of jet-engine for oil well fire fighting which is a latest in kind is described and analyzed. For this purpose, more familiarization with this system and some knowledge’s such as hydrodynamics characteristic of nominated area, traditional ways of fire fighting in region, different types of jet engines available type of offshore vessels, type of flame and their characteristic are required, which after studying and analyzing above fields in details, the use of turbojet motors and barge has been chosen for the case to obtain optimum specification os this turbojet motors and required dimensions of barge Some information about oil well shuch as, fluid output, speed rate...
Formation of Plasma Electrolytic Oxidation Coating on Mg-Ti Coupl Joint with Friction stir Welding Process and Evaluation its Properties
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Plasma electrolytic oxidation is the novel surface engineering technology that used as the low cost and eco-friendly method for improvement of corrosion resistance and wear resistance of Mg and Ti alloys. The aim of this investigation is firstly joint the Ti and Mg, then optimization of coating process condition of Ti-Mg couple for achieve the best corrosion and wear resistance of coating. For this purpose, initially Ti and Mg were joint together by friction stir welding treatment and then the effect of coating variable such as type of electrolyte, coating voltage, coating time and the concentration of the bath constitute, on the coating properties were investigated, and then the effect of...
On maximal and minimal linear matching property
, Article Algebra and Discrete Mathematics ; Volume 15, Issue 2 , 2013 , Pages 174-178 ; 17263255 (ISSN) ; Darafsheh, M. R ; Sharif University of Technology
2013
Abstract
The matching basis in field extentions is in-troduced by S. Eliahou and C. Lecouvey in [2]. In this paper we define the minimal and maximal linear matching property for field extensions and prove that if K is not algebraically closed, then K has minimal linear matching property. In this paper we will prove that algebraic number fields have maximal linear matching property. We also give a shorter proof of a result established in [6] on the fundamental theorem of algebra
A rigorous security analysis of a decentralized electronic voting protocol in the universal composability framework
, Article Journal of Information Security and Applications ; Volume 43 , 2018 , Pages 99-109 ; 22142134 (ISSN) ; Rezaei Aliabadi, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Designing an efficient and secure electronic voting (e-voting) protocol without the presence of trusted authorities, known as decentralized voting protocols, is one of the most interesting and challenging problems in cryptography. In these protocols the outcome of the protocol is computed by voters collaborating with each other. We provide a rigorous proof of security of a decentralized e-voting protocol proposed by Khader et al. in the Universal Composability (UC) Framework. This protocol is the state-of-the-art decentralized e-voting protocol in terms of efficiency and security, whose security has only been justified against a set of desired properties required in e-voting protocols. For...
Synthesis and Characterization of Cobalte Ferrite and Nickel Ferrite Nanocatalysts and Their Application in the C-X Bond Activation Reaction
, M.Sc. Thesis Sharif University of Technology ; Matloubi Moghaddam, Firouz (Supervisor)
Abstract
Nowadays application of metallic catalysts in many of the organic reactions has been developed; therefore, different types of catalysts have been produced and used. In this way, in the first part of this thesis magnetic cobalt ferrite and nickel ferrite nanocatalysts were synthesized using co-precipitation method and their activity as catalyst was investigated in C-O bond formation reaction. This reaction was carried out between different types of aryl alcohols and aryl halides with good to excellent yields. The results showed that using N,N-dimethyl formamide as solvent, potassium carbonate as base and 5mol% of nanocatalysts at 80°C are the optimized condition for this reaction. In the...
Continuous monitoring of safety performance
, Article Total Safety and the Productivity Challenge ; 2019 , Pages 126-140 ; 9781351609074 (ISBN); 9781138091306 (ISBN) ; Sharif University of Technology
Taylor and Francis
2019
Abstract
Key performance indicators (KPIs) are the fundamental building blocks in measuring and monitoring processes of safety management. This chapter describes a classification of safety KPIs and a review of literature leads to a new framework. It aims to develop a logical selection and aggregation methodology for generating a single number that reflects safety performance. Determining a mechanism for performance measurement and monitoring is a key part of any management system, and this has a higher importance for total safety management. Personal safety deals with the prevention of occupational accidents that usually have low severities and high frequencies. The measurement of safety has been...
Continuous monitoring of safety performance
, Article Total Safety and the Productivity Challenge ; 2019 , Pages 126-140 ; 9781351609074 (ISBN); 9781138091306 (ISBN) ; Sharif University of Technology
Taylor and Francis
2019
Abstract
Key performance indicators (KPIs) are the fundamental building blocks in measuring and monitoring processes of safety management. This chapter describes a classification of safety KPIs and a review of literature leads to a new framework. It aims to develop a logical selection and aggregation methodology for generating a single number that reflects safety performance. Determining a mechanism for performance measurement and monitoring is a key part of any management system, and this has a higher importance for total safety management. Personal safety deals with the prevention of occupational accidents that usually have low severities and high frequencies. The measurement of safety has been...
Flux dynamics in Y358 and Gd358 superconductors
, Article Journal of Superconductivity and Novel Magnetism ; Vol. 27, issue. 3 , 2014 , pp. 741-748 ; ISSN: 15571939 ; Akhavan-Farshchi, Y ; Akhavan, M ; Sharif University of Technology
2014
Abstract
We have studied the thermally activated flux creep in the newly fabricated superconductors Y3Ba5Cu8O18+δ and Gd3Ba5Cu8O18+δ with transition temperature above 100 K. The thermally activated flux creep model explains the electron share in the magnetoresistivity of the samples in the vicinity of transition temperature T c . The activation energy U in a magnetic field below 15 kOe has been calculated by the corrected thermally activated flux creep model; and the pinning energy is exponentially related to the magnetic field
Zn–Ni electrophosphating on galvanized steel using cathodic and anodic electrochemical methods
, Article Surface and Coatings Technology ; Volume 306 , 2016 , Pages 497-505 ; 02578972 (ISSN) ; Afshar, A ; Aliabadi, A ; Sharif University of Technology
Elsevier B.V
2016
Abstract
Electrophosphating is the novel method for accelerating the low temperature phosphating bath. This method can be performed as cathodic and anodic treatments. Both of them influence the coating deposition mechanism and therefore coating properties. In this study Zn–Ni electrophosphate coating was applied on galvanized steel using cathodic and anodic electrochemical methods. Microstructure, composition and corrosion resistance of coating were characterized by using a scanning electron microscopy, X-ray diffraction method and potentiodynamic polarization test respectively. The results of this study indicated that, by using cathodic method, compact phosphate coating with high corrosion...
Zn-Ni Electrophosphating on galvanized steel using cathodic and anodic electrochemical methods
, Article Surface and Coatings Technology ; January , 2015 ; 02578972 (ISSN) ; Afshar, A ; Aliabadi, A ; Sharif University of Technology
Elsevier
2015
Abstract
Electrophosphating is the novel method for accelerating the low temperature phosphating bath. This method can be performed as cathodic and anodic treatments. Both of them influence the coating deposition mechanism and therefore coating properties. In this study Zn-Ni electrophosphate coating was applied on galvanized steel using cathodic and anodic electrochemical methods. Microstructure, composition and corrosion resistance of coating were characterized by using a scanning electron microscopy, X-ray diffraction method and potentiodynamic polarization test respectively. The results of this study indicated that, by using cathodic method, compact phosphate coating with high corrosion...
A new Y-based HTSC with Tc above 100 K
, Article Physica C: Superconductivity and its Applications ; Volume 469, Issue 22 , 2009 , Pages 2012-2014 ; 09214534 (ISSN) ; Akhavan Farshchi, Y ; Akhavan, M ; Sharif University of Technology
2009
Abstract
In search of finding the dominant mechanism in high temperature superconductivity phenomena, the Y3Ba5Cu8O18 compound was synthesized through the standard solid-state reaction technique. Characteristic XRD experiment was performed on the samples and was analyzed by the MAUD software refinement program. The analysis results indicate a 358 phase structure with the initial nominal stoichiometry. The electrical resistivity and its behavior under different magnetic field were measured. The electrical resistivity indicates the transition temperature Tc onset = 102 K with transition width ΔTc = 2.4 K. This is the first observation of such a high transition temperature in the Y-based compound....
Plasma electrolytic oxidation of Mg-Ti couple metals fabricated by friction stir welding: Characterization and corrosion studies
, Article Materials Research Express ; Volume 6, Issue 8 , 2019 ; 20531591 (ISSN) ; Ghorbani, M ; Barati Darband, G ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
In this study, plasma electrolytic oxidation (PEO) of Ti-Mg couple metal fabricated by friction stir welding (FSW) in silicate base solution has been addressed and effect of silicate concentration in the electrolyte on coating properties was studied. Microstructure, composition and corrosion resistance of coating were characterized using scanning electron microscopy(SEM), X-ray diffraction (XRD) and potentiodynamic polarization methods. Ti-Mg couple were successfully coated simultaneously in silicate electrolyte and results of this study indicated that silicate concentration has a considerable impact on microstructure and corrosion resistance of the coating. In 5 g l-1 sodium silicate...
Parametric Analysis of Thermomechanical Stresses in Functionally Graded Materials Under in-phase and out-of-phase Loading
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
Using Functionally Graded Materials (FGMs) in hot sections of aged aircrafts is one of the most important ways for life extending of Thermal Barrier Coatings (TBCs). Sudden variation of thermal stresses in interface of bond coat and ceramic coat layers could be changed to gradual variation with use of FGMs. The stress in FGMs has been the subject of several researches. Both macro and micromechanical modeling approaches have been used in these studies. In the macro mechanical approach, FGM is modeled as a multi-layer composite in which mechanical properties of each layer is found by averaging the properties and volume fraction of FGM constituents through the thickness of the layer. In this...
Study of Carbon Monoxide Emission and Dispersion in Long Motorway Spaces: A Case Study of Tohid Tunnel
,
M.Sc. Thesis
Sharif University of Technology
;
Vaziri, Manouchehr
(Supervisor)
Abstract
Vehicular tunnels are very prone to excess of air pollution due to their enclosed nature. Inadequate ventilation combined with high traffic flow result in elevated concentration of vehicle-induced air pollutants, which can pose serious health hazards. This study was carried out in the longest vehicular tunnel in Tehran, locally referred to as Tohid tunnel. Traffic flow characteristics, carbon monoxide level and it's dispersion along the tunnel were investigated in this project. Data were collected in 4 days and 3 times a day, 7-8 in the morning, 11-12 and 17-18 in the evening. Measurements were conducted at fixed locations, outside the tunnel,...
Security Analysis of Decentralized E-voting Protocols in the Universal Composability Framework
, M.Sc. Thesis Sharif University of Technology ; Khazaei, Shahram (Supervisor)
Abstract
Designing efficient and secure electronic voting protocols without the presence of trusted authorities, which are known as decentralized voting protocols, is one of the most interesting and challenging problems in cryptography. In these protocols the outcome of the protocol is determined by voters collaborating with each other. Since voting is a significant concept in every society, the correctness and security of voting protocols are important. For security analysis of electronic voting protocols, an intuitive proof is not enough and we require a comprehensive approach that provides provable security. In this thesis, we use universal composition framework to analyze a decentralized e-voting...
Universal image steganalysis using singular values of DCT coefficients
, Article 2013 10th International ISC Conference on Information Security and Cryptology ; 2013 ; Gaemmaghami, S ; Sharif University of Technology
IEEE Computer Society
2013
Abstract
We propose a blind image steganalysis method based on the Singular Value Decomposition (SVD) of the Discrete Cosine Transform (DCT) coefficients that are revisited in this work. We compute geometric mean, mean of log values, and statistical moments (mean, variance and skewness) of the SVDs of the DCT sub-blocks that are averaged over the whole image to construct a 480-element feature vector for steganalysis. These features are fed to a Support Vector Machine (SVM) classifier to discriminate between stego and cover images. Experimental results show that the proposed method outperforms most powerful steganalyzers when applied to some well-known steganography algorithms
Intelligent clustering in wireless sensor networks
, Article 1st International Conference on Networks and Communications, NetCoM 2009, 27 December 2009 through 29 December 2009, Chennai ; 2009 , Pages 12-17 ; 9780769539249 (ISBN) ; Movaghar, A ; Sharif University of Technology
2009
Abstract
Minimization of the number of cluster heads in a wireless sensor network is a very important problem to reduce channel contention and to improve the efficiency of the algorithm when executed at the level of cluster-heads. In this paper, we propose an efficient method based on genetic algorithms (GAs) to solve a sensor network optimization problem. Long communication distances between sensors and a sink in a sensor network can greatly drain the energy of sensors and reduce the lifetime of a network. By clustering a sensor network into a number of independent clusters using a GA, we can greatly minimize the total communication distance, thus prolonging the network lifetime. Simulation results...
The effect of rippled graphene sheet roughness on the adhesive characteristics of a collagen-graphene system
, Article International Journal of Adhesion and Adhesives ; Volume 64 , 2016 , Pages 9-14 ; 01437496 (ISSN) ; Shamloo, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
A great amount of effort has been made in order to reach a more precise understanding of the adhesion phenomenon that happens as a vital component of several biological systems. Therefore, a firm understanding of the important factors that influence this phenomenon is of special importance in triggering the adhesive characteristics of different biological, bio-inspired and synthetic materials in fields such as tissue engineering. In this study the adhesive characteristics of a multi-material system consisting of the frequently used synthetic material, graphene, in the form of armchair-configuration sheets, and an important biological filament which is type 1 Collagen consisting of 3 alpha...
Using makeup water to recycle cooling tower evaporated water: A feasibility study using experimental data
, Article International Journal of Energy Technology and Policy ; Volume 17, Issue 3 , 2021 , Pages 227-238 ; 14728923 (ISSN) ; Heidari, E ; Sharif University of Technology
Inderscience Publishers
2021
Abstract
Wet cooling towers are one of the most water-intensive technologies, which are widely used in air conditioning applications, especially in dry regions. Considering the current water crisis around the world, it is essential to improve the design of these cooling towers to reduce their water consumption, while maintaining their cooling performance. Makeup water of cooling tower is usually a constant-temperature water which is cold enough to condensate the moisture content of the cooling tower exhaust air. Therefore, it has great potential to recycle water evaporation of cooling towers, which is not considered so far. This paper investigates a novel design for cooling towers utilising the...