Search for: deposits
Total 660 records
Article Journal of the Japan Petroleum Institute ; Volume 47, Issue 1 , 2004 , Pages 27-31 ; 13468804 (ISSN) ; Rashtchian, D ; Tohidi, B ; Jamialahmadi, M ; Sharif University of Technology
Asphaltene precipitation and deposition is one of the main problems in some of the oil fields. The deposited asphaltene results in partial or total blockage of the wellstring and reducing or completely seizing oil production. Asphaltene deposition problems have been experienced in the field for a long time. Although, the asphaltene precipitation has been studied thoroughly and different parameters that effects this process has been investigated but little work has been carried out in the asphaltene deposition across the production system of flowing oil well. This paper introduces a new comprehensive model for description of asphaltene deposition behavior in wellstring. The mechanisms of...
Article Iranian Journal of Physics Research ; Volume 17, Issue 2 , 2017 , Pages 263-268 ; 16826957 (ISSN) ; Zavarian, A. A ; Hafezi, F ; Sharif University of Technology
Isfahan University of Technology 2017
In this paper, the vacuum film deposition through electron beam evaporation has been reviewed and the effect of magnetic field on the operation of this system has been explained. Then, the magnetic field distribution due to magnetic components configuartion of a commercial evaporation source with 270-degree electron beam gun (manufactured by Sharif University Branch of ACECR), has been simulated by means of a finite element software, ANSYS. The simulation result was verified by comparing with the results obtained from measurement by Hall Effect sensor. Furthermore, by using the ray-tracing capability of the software, the capability of the magnetic lens of this device for electron beam...
Article Journal of Mining Science ; Volume 40, Issue 3 , 2004 , Pages 310-320 ; 10627391 (ISSN) ; Rezai, B ; Vossoughi, M ; Osanloo, M ; Sharif University of Technology
The results are presented for the investigations of sulfur removal from coal by a mixed culture of microorganisms. Optimal conditions of the process are established (pH, size of coal particles, pulp density, temperature, etc.). They make it possible to reduce the content of pyrite and total sulfur by 91.84 and 53.5%, respectively. The decrease in ash content of coal under its leaching is noted. © 2004 Springer Science+Business Media, Inc
Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 29, Issue 2 , 2010 , Pages 131-142 ; 10219986 (ISSN) ; Rashtchian, D ; Tohidi, B ; Jamialahmadi, M ; Sharif University of Technology
Asphaltene precipitation and deposition is a serious problem in many Iranian fields. The deposited asphaltene results in partial or total blockage of the wellbore and wellstring reducing or completely seizing oil production. This paper studies the asphaltene problem and mitigation methods in wellstring systematically. It presents new approach based on the combination of thermodynamic modeling of asphaltene precipitation with hydrodynamic well modeling. The developed model is capable to determine the asphaltene precipitation and deposition interval through the wellstring. Therefore, it could study the effect of hydrodynamic parameters such as wellhead pressure, well flow-rate and tubing size...
Article Journal of Statistical Mechanics: Theory and Experiment ; Issue 9 , 2006 ; 17425468 (ISSN) ; Saberi, A. A ; Azimirad, R ; Moshfegh, A. Z ; Rouhani, S ; Sharif University of Technology
We have studied the effect of annealing temperature on the statistical properties of WO3 surface using atomic force microscopy (AFM) techniques. We have applied both level crossing and structure function methods. Level crossing analysis indicates an optimum annealing temperature of around 400°C at which the effective area of the WO3 thin film is maximum, whereas the composition of the surface remains stoichiometric. The complexity of the height fluctuation of surfaces was characterized by roughness, the roughness exponent and the lateral size of surface features. We have found that there is a phase transition at around 400°C from one set to two sets of roughness parameters. This happens due...
Article DETC2005: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Long Beach, CA, 24 September 2005 through 28 September 2005 ; Volume 1 A , 2005 , Pages 755-760 ; 0791847381 (ISBN) ; Fathi, A ; Khajepour, A ; Toyserkani, E ; Sharif University of Technology
Laser Powder Deposition technique is an advanced production method with many applications. Despite this fact, reliable and accurate control schemes have not yet fully developed for this method. This article presents method for in time identification of the process for modeling and adaptation of proper control strategy. ARMAX structure is chosen for system model. Recursive least square method and Kalman Filter methods are adopted for system identification, and their performance are compared. Experimental data was used for system identification, and proper filtering schemes are devised here for noise elimination and increased estimation results. It was concluded that although both methods...
Article Energy and Fuels ; Volume 26, Issue 10 , June , 2012 , Pages 6186-6199 ; 08870624 (ISSN) ; Miri, R ; Ayatollahi, S ; Escrochi, M ; Sharif University of Technology
Oil production from asphaltenic oil reservoirs has always encountered difficulties, such as plugging and unpredictable fluid properties. To physically recognize the aspects of asphaltene deposition, several dynamic and static asphaltene deposition tests were designed and performed on one of the giant south Iranian oil reservoirs using dead and live crude oil and real core samples. Moreover, the effects of fluid velocity on the extent of damage were investigated. It was found that surface deposition of asphaltene particles is the main source of formation damages in the porous media and the resulting permeability impairment obeys an exponential behavior. All of the experiments confirm that...
Article Journal of the American Ceramic Society ; Volume 100, Issue 3 , 2017 , Pages 901-910 ; 00027820 (ISSN) ; Aliofkhazraei, M ; Hosseinali, M ; Sharif University of Technology
Blackwell Publishing Inc 2017
ZnO–CeO2 nanoparticles were synthesized by microwave combustion and deposited by electrophoretic deposition (EPD). The effect of using two different alcohols, ethanol and methanol, was investigated on EPD behavior and morphology of deposited film. Moreover, the effect of concentration of nanoparticles and applied voltage on the mass of deposit and the variation in the current density were investigated. With a change in the alcohol type, the surface morphology of deposition changed and some voids were observed on the deposition surface in ethanol. In all cases, with increasing concentration of nanoparticles in suspension, the number of developed cracks increased. Besides, a rise in voltage...
Article International Journal of Heat and Mass Transfer ; Volume 52, Issue 19-20 , 2009 , Pages 4624-4634 ; 00179310 (ISSN) ; Soltani, B ; Müller Steinhagen, H ; Rashtchian, D ; Sharif University of Technology
Asphaltene deposition is one of the unresolved problems in oil industries. Little information is available on the critical question of "how fast" the flocculated asphaltene particles deposit across the production wells from the flowing oil. In this study, the mechanisms of deposition of flocculated asphaltene particles from oil have been studied experimentally and theoretically under forced convective conditions using an accurate thermal approach. The effects of oil velocity, flocculated asphaltene concentration and temperature on the rate of asphaltene deposition are investigated. It is observed that during the first few weeks the deposition mechanism is dominant and the erosion of the...
Article Petroleum Science and Technology ; Volume 31, Issue 2 , 2013 , Pages 129-141 ; 10916466 (ISSN) ; Schaffie, M ; Kharrat, R ; Ghazanfari, M. H ; Ghoodjani, E ; Sharif University of Technology
The authors studied deposition and entrainment of asphaltene particles as major mechanisms that occur in porous media. Deposition mechanisms that contribute to permeability reduction and entrainment of deposited particle improve the damaged permeability value. While in most previous works the effects of entrainment mechanism are considered negligible, in this study miscible CO2 injection tests were conducted by core flood apparatus to investigate the effect of asphaltene deposition on permeability and porosity alterations. Results indicated that proposed model for entrainment mechanism is affected by deposition mechanism. The asphaltene deposition core's characteristics have undeniable roles...
Application of artificial neural networks to prediction of chemical composition of electrodeposited Ni-Mo thin films, Article ECS Transactions ; Volume 50, Issue 52 , Oct , 2012 , Pages 63-71 ; 19385862 (ISSN) ; Rouhaghdam, A. S ; Aliofkhazraie, M ; Shahrabi, T ; Ashrafi, A ; Seddighian, A ; Sharif University of Technology
Present research represents the application of artificial neural networks to predict the chemical composition of electrodeposited Ni-Mo thin films. Artificial neural networks commonly are utilized as a prediction tools so that these networks could approximately find kind of logic relationships between inputs and target; they fitted appropriate coefficient and weighting factors to the inputs which are proportional to their importance. In order to evaluate the model developed, experimental results were compared with the predicted ones. However, more data are required to train more reliable prediction models, presents study revealed an acceptable error less than 1% between predicted values and...
M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem ; Ghorbani, Mohammad
Platinum nanowires were prepared by electrodeposition in polycarbonate membrane, with different average diameter of nanowires about 15, 50 and 100 nm and the height about 6 µm. Kinetics of electrodeposition process were studied by electrochemical techniques such as voltammetry and chronoamperometry methods. Diffusion coefficient was then calculated from the electrochemical parameters and consequently the density of primer nuclei was extracted. The morphology of Pt nanowires was characterized by SEM, TEM and EDX. The results show that growing Nanowires on the surface of template is branch-like. The electro-oxidation of methanol and hydrogen on this electrode is investigated at room...
Characterization and antibacterial performance of electrodeposited chitosan–vancomycin composite coatings for prevention of implant-associated infections [electronic resource], Article Journal of Materials Science and Engineering: C ; 1 August 2014, Volume 41, Pages 240–248 ; Tamjid, E ; Simchi, A. (Abdolreza) ; Sharif University of Technology
Orthopaedic implant-associated infections are one of the most serious complications in orthopaedic surgery and a major cause of implant failure. In the present work, drug-eluting coatings based on chitosan containing various amounts of vancomycin were prepared by a cathodic electrophoretic deposition process on titanium foils. A three-step release mechanism of the antibiotic from the films in a phosphate-buffered saline solution was noticed. At the early stage, physical encapsulation of the drug in the hydrogel network controlled the release rate. At the late stage, however, in vitro degradation/deattachment of chitosan was responsible for the controlled release. Cytotoxicity evaluation of...
Improved efficiency of dye-sensitized solar cells based on a single layer deposition of skein-like TiO 2 nanotubes, Article Journal of the American Ceramic Society ; Vol. 97, issue. 9 , 2014 , pp. 2873-2879 ; ISSN: 00027820 ; Mohammadi, M. R ; Madaah Hosseini, H. R ; Sharif University of Technology
We present a new TiO2 morphology, featuring high surface area and open structure, synthesized by a two-step chemical route for the manufacture of dye-sensitized solar cells (DSSCs). This construct is sets of intertwined one-dimensional (1D) nanostructures (i.e., nanotubes), so-called skein-like nanotubes (NTs). Such morphology is produced by a combination of TiC oxidation and hydrothermal processes. The mesoporous TiO2 nanoparticles, as the product of TiC oxidation operation, is used as the precursor of hydrothermal process to grow the skein-like NTs. The effect of processing parameters of TiC oxidation and hydrothermal processes is studied. The skein-like morphology enables to eliminate the...
Article Journal of the European Ceramic Society ; Volume 33, Issue 10 , 2013 , Pages 1815-1823 ; 09552219 (ISSN) ; Yar, A. Y ; Vafaeenezhad, S ; Sani, M. A. F ; Simchi, A ; Sharif University of Technology
Functionally-graded NiO-8. mol % YSZ composite films were prepared by a controlled voltage-decay electophoretic deposition (EPD) process. The films consisted of three layers with varying NiO concentrations and porosities. Effects of different parameters including the type of the organic media, solid concentration, NiO:YSZ ratio, and iodine on the stability of EPD suspensions and deposition kinetics were studied. A stable NiO-YSZ suspension was attained in isopropanol with NiO-YSZ ratio of 60:40 and iodine concentration of 0.5. mM. The composite film contained varying NiO concentration from 46. wt.% near the substrate to 32. wt.% close to the electrolyte with 42. wt% NiO in the intermediate...
Silver selenide as a potential electro-catalyst for l-ascorbic acid electro-oxidation in alkaline solution, Article Electrocatalysis ; Volume 2, Issue 4 , December , 2011 , Pages 331-336 ; 18682529 (ISSN) ; Majari Kasmaee, L ; Sharif University of Technology
Cathodically deposited Ag 2Se, to form a 1-μm-thick film, characterized by energy dispersive X-ray analysis and scanning electron microscopy, showed high electro-catalytic activity for l-ascorbic acid oxidation in alkaline solution. The onset of the process was about 80 mV cathodic of that previously observed on Ag under the same conditions and far superior over glassy carbon and Pt. The values of the exchange current density, standard heterogeneous rate constant, and transfer coefficient of the reaction were 1. 65 × 10 -4 A cm -2, 4. 35 × 10 -7 cm s -1, and 0. 60, respectively. Diffusion coefficient of l-ascorbate di-anion was also measured and was around 7. 00 × 10 -6 cm 2 s -1
Nanoparticulate hollow TiO 2 fibers as light scatterers in dye-sensitized solar cells: Layer-by-layer self-assembly parameters and mechanism, Article ChemPhysChem ; Volume 12, Issue 5 , 2011 , Pages 966-973 ; 14394235 (ISSN) ; Tajabadi, F ; Shooshtari, L ; Taghavinia, N ; Sharif University of Technology
Hollow structures show both light scattering and light trapping, which makes them promising for dye-sensitized solar cell (DSSC) applications. In this work, nanoparticulate hollow TiO 2 fibers are prepared by layer-by-layer (LbL) self-assembly deposition of TiO 2 nanoparticles on natural cellulose fibers as template, followed by thermal removal of the template. The effect of LbL parameters such as the type and molecular weight of polyelectrolyte, number of dip cycles, and the TiO 2 dispersion (amorphous or crystalline sol) are investigated. LbL deposition with weak polyelectrolytes (polyethylenimine, PEI) gives greater nanoparticle deposition yield compared to strong polyelectrolytes...
Investigation of the structure and electrical properties of strontium titanate thin films growth by pulsed laser deposition method, Article Journal of Ceramic Processing Research ; Volume 17, Issue 1 , 2016 , Pages 26-29 ; 12299162 (ISSN) ; Mahdavi, S. M ; Tahmasebi, N ; Sharif University of Technology
Hanyang University 2016
In this paper, we have studied the properties of SrTiO3 thin films which have been deposited on Si/Ti/Pt substrates using pulsed laser deposition technique. The as-deposited films were annealed at temperature of 700 °C in oxygen environment for 1 h. The surface morphology, crystalline phase and chemical composition of the films were characterized by AFM, XRD and XPS techniques, respectively. The XRD data show that phase transition from amorphous to polycrystalline structure happens and also the lattice constant enhances during annealing process. This enhancement can be related to oxygen vacancies in thin films. The XPS data show partial lack of titanium atoms on the surface. The AFM analysis...
Electrodeposition of Zn–Ni–P compositionally modulated multilayer coatings: An attempt to deposit Ni–P and Zn–Ni alloys from a single bath, Article Electrochemistry Communications ; Volume 81 , 2017 , Pages 93-96 ; 13882481 (ISSN) ; Ghorbani, M ; Sharif University of Technology
Elsevier Inc 2017
The effects of bath composition and deposition variables on the electrodeposition of Zn–Ni–P alloys were studied in order to develop a single bath for deposition of Ni–P/Zn–Ni compositionally modulated multilayer coatings (CMMCs). The basis for development of the bath was a large increase in the Ni deposition rate compared to that of Zn at low deposition overpotentials combined with the impossibility of codeposition of Zn with P. EDS analysis demonstrated that the deposits obtained from the Zn–Ni–P bath at low overpotentials were practically all Ni–P, while the alloy deposited at high overpotentials was mainly Zn–Ni with around 3.2 wt% P content. © 2017 Elsevier B.V
Article Scientia Iranica ; Volume 24, Issue 4 , 2017 , Pages 1975-1984 ; 10263098 (ISSN) ; Saidi, M. S ; Ahmadi, G ; Sharif University of Technology
Sharif University of Technology 2017
The prediction of deposition efficiency of submicron particles in the pulmonary alveoli has received special attention due to its importance for drug delivery systems and for assessing air pollutants health risks. In this work, the pulmonary alveoli of a healthy human are idealized by a three-dimensional honeycomb-like configuration and a fluid-structure interaction analysis is performed. In contrast to previous works in which the inlet flow rate is predefined, in this model, a negative pressure is imposed on the outside surface of the flalveolus which causes air to flow in and out of the alveolus. The resulting flow patterns confirmed that there was no circulation in the terminal alveolus....