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Exprimental Study of Various Modes of Electrospray for Different Nozzles
, M.Sc. Thesis Sharif University of Technology ; Morad, Mohammad Reza (Supervisor)
Abstract
Electrospray is an interesting method to produce spray. This study has an insight on electrospraying phenomenon and its effective parameters. All modes, the forces and the situation to establish has been investigated for ethanol. Suitable configuration is introduced and for different flow rates and voltages the phenomenon is studied. Images are captured by two camera (high speed camera and high resolution camera) by using two method (shadowgraphy and light scattering). In the respect of producing fine and monodisperse droplets in cone-jet mode the stability of this mode is imported to enlarge. The special nozzle is design to increase stability of cone-jet mode even 70 times of using...
Layer-by-layer self assembly deposition and characterization of TiO 2 nanoparticles by using a short chain polycation
, Article EPJ Applied Physics ; Volume 48, Issue 1 , 2009 , Pages 10602p1-10602p7 ; 12860042 (ISSN) ; Taghavinia, N ; Sharif University of Technology
2009
Abstract
Using low molecular weight polyethylenimine (PEI), transparent thin films of TiO2 nanoparticles were prepared by layer-by-layer self assembly method. UV-visible spectrophotometry was employed in a quantitative manner to monitor the adsorbed mass of TiO2 and PEI after each dip cycle. The adsorption of both TiO2 and PEI showed a saturation dip time of 10 min. The effect of dip time on the growth mode and surface morphology was investigated by scanning electron microscopy (SEM) and non-contact atomic force microscopy (AFM). It was found that growth proceeds in the form of laterally broad islands in case of short dip times, and taller but laterally smaller islands in case of longer dip times. A...
A Very stable high throughput taylor cone-jet in electrohydrodynamics
, Article Scientific Reports ; Volume 6 , 2016 ; 20452322 (ISSN) ; Rajabi, A ; Razavi, M ; Pejman Sereshkeh, S. R ; Sharif University of Technology
Nature Publishing Group
2016
Abstract
A stable capillary liquid jet formed by an electric field is an important physical phenomenon for formation of controllable small droplets, power generation and chemical reactions, printing and patterning, and chemical-biological investigations. In electrohydrodynamics, the well-known Taylor cone-jet has a stability margin within a certain range of the liquid flow rate (Q) and the applied voltage (V). Here, we introduce a simple mechanism to greatly extend the Taylor cone-jet stability margin and produce a very high throughput. For an ethanol cone-jet emitting from a simple nozzle, the stability margin is obtained within 1 kV for low flow rates, decaying with flow rate up to 2 ml/h. By...
Prediction of shear strength parameters of hydrocarbon contaminated sand based on machine learning methods
, Article Georisk ; 2020 ; Mojtahedi, S. F. F ; Taherabadi, E ; Soleymani, K ; Pejman, M ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
The objective of this paper is to predict the effect of hydrocarbon contamination on the shear strength parameters of sand by using various machine learning platforms. Multilayer perceptron, support vector machine, random forest, gradient boosting method, and multi-output support vector machine were methods used to predict the hydrocarbon contamination impacts on the internal friction angle and cohesion of contaminated sand. Random forest exhibited the best results for cohesion, whereas, for the friction angle, the gradient boosting method outperformed other approaches. Moreover, the multi-output support vector machine yielded better results than those pertaining to a single support vector...
Improving the Efficiency of On-chip 3D Stacked DRAM in Server Processors
, M.Sc. Thesis Sharif University of Technology ; Sarbazi-Azad, Hamid (Supervisor) ; Lotfi Kamran, Pejman (Co-Advisor)
Abstract
Big-data server workloads have vast datasets, and hence, frequently access off-chip memory for data. Consequently, server workloads lose significant performance potential due to off-chip latency and bandwidth walls. Recent research advocates using 3D stacked DRAM to break the walls. As 3D stacked DRAM cannot accommodate the whole datasets of server workloads, most proposals use 3D DRAM as a large cache. Unfortunately, a large DRAM cache imposes latency overhead due to (1) the need for tag lookup and (2) inefficient utilization of on-chip and off-chip bandwidth, and as a result, lowers the benefits of 3D stacked DRAM. Moreover, storing the tags of a multi-gigabyte DRAM cache requires changes...
Simulation and Study of Iso-Dose Curve for Asymmetrical Balloon in Balloon-Brachytherapy with Cs-131
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Abolfazl (Supervisor) ; Shirmardi, Pejman (Supervisor)
Abstract
Incidence of brain metastases (BM) from any tumor varies according to the method of data collection and date reported, ranging from 8 to 14 per 100,000 people per year. According to current population, about 6400 to 11000 BM Patients per year is expected. Without treatment, prognosis is dismal with survival of only 1–2 months. However, survival can be extended to 3–6 months with whole-brain radiotherapy (WBRT) and to 11 months with either surgery followed by adjuvant WBRT or surgery plus adjuvant stereotactic radiosurgery (SRS). Intravascular brachytherapy (generally iodine-125 (125I)) into the surgical cavity is another treatment strategy. 125I has been shown to confer local control...
Designing Instruction Prefetcher with Low Area Overhead for Server Workloads
,
M.Sc. Thesis
Sharif University of Technology
;
Sarbazi Azad, Hamid
(Supervisor)
;
Lotfi Kamran, Pejman
(Co-Supervisor)
Abstract
L1 instruction cache misses creates a crucial performance bottleneck for server applications. Server applications extensively use operating system services, and as such, have large instruction footprint that dwarfs instruction cache size. Meanwhile, fast access requirements preclude enlarging instruction cache that can hold the whole instruction footprint of current server workloads. Prior works proposed using hardware prefetching schemes to eliminate or reduce the effect of instruction cache misses. They use the fact that server application instruction sequences are repetitive. So by recording and prefetching based on such sequesnces, L1 insruction misses could be reduced. While they...
Liquid jet trajectory and droplet path influenced by combined cross flow and electric fields
, Article Chemical Engineering Science ; Volume 181 , 18 May , 2018 , Pages 114-121 ; 00092509 (ISSN) ; Morad, M. R ; Rahbari, N ; Pejman Sereshkeh, S. R ; Razavi, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This study investigates an ethanol liquid jet subjected to combination of an air crossflow and a normal electric field. The results on the liquid jet trajectory and subsequent droplets flight paths are presented. The liquid jet trajectory was found as a function of two non-dimensional quantities; the liquid jet to the crossflow momentum ratio and the electroinertial number. The electroinertial number is defined as the ratio between the liquid jet specific momentum and the electric force. A correlation is introduced for the jet trajectory in low crossflow speeds and electric field intensities. The same two quantities control the detached droplets flight paths. Satellite droplets flight angles...
Speculative Path Setup for Fast Data Delivery in Server Processors
, M.Sc. Thesis Sharif University of Technology ; Sarbazi-Azad, Hamid (Supervisor) ; Lotfi-Kamran, Pejman (Co-Advisor)
Abstract
Server workloads operate on large volumes of data. As a result, processors executing these workloads encounter frequent L1-D misses. An L1-D miss causes a request packet to be sent to an LLC slice and a response packet to be sent back to the L1-D, which results in high overhead. While prior work targeted response packets, this work focuses on accelerating the request packets through a simple-yet-effective predictor. Upon the occurrence of an L1-D miss, the predictor identifies the LLC slice that will serve the next L1-D miss and a circuit will be set up for the upcoming miss request to accelerate its transmission. When the upcoming miss occurs, the resulting request can use the already...
Prediction of Density, Surface Tension and Viscosity of Ionic Liquids using Artificial Intelligence
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
Ionic liquids due to their unique physical and chemical properties are widely used in various fields of chemistry and chemical engineering. Determining properties of ionic liquids can be difficult, time consuming or even impossible. In first step of this study the IL thermo database was chosen as source of experimental data of ionic liquids. Viscosity, density, surface tension and melting temperature of ionic liquids based on bis(trifluoromethylsulfonyl)imide anion with cations imidazolium, pyridinium, pyrrolidinium, piperidinium and ammonium were modeled using QSPR approach. Linear and nonlinear models were built by means of multiple linear regression (MLR), multilayer perceptron neural...
Preparation, Characterization and Catalytic Application of Some Polyoxometalates for Esterification Reaction
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
Catalytic esterification of acetic acid with 1-hexanol was investigated over polyoxometalates. H3PW12O40 and H3PMo6W6O40 polyoxometalates with keggin structures were synthesized. Catalytic activity and recyclability of them were improved by loading on the γ-Al2O3 with impregnation method and Cs, K and NH4 salts preparing.Catalysts were characterized by XRD, SEM, FT-IR, BET, DRS and NMR techniques. According to XRD's results, catalysts have ace-centered cubic crystal systems. Loading on supports and preparing the salts do not destroy the structures of polyoxometalates. SEM images show the uniformity of catalysts' surface and catalysts' fixing on the support. It was seen that the keggin...
Electrochemical Degradation of Organic Pollutants in the Presence of Spinel Cobalt Ferrite Nanoparticles: Investigation of the Effective Parameters and Evaluation of Degradation Kinetics
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
In this study, CoFe2O4/CuO nanocomposite was synthesized by hydrothermal method and utilized for removal of metronidazole in electro-Fenton process. Nanocomposite was characterized by FT-IR, XRD, FE-SEM, VSM and BET methods. The Results of XRD patterns confirmed the monoclinic structure formation for copper(Ⅱ) oxide and the spinel structure for CoFe2O4. The FE-SEM images displayed the formation of CuO nanosheets for copper(Ⅱ) oxide and the decoration of cobalt ferrite nanoparticles on the surface of CuO nanosheets. Measurement of the surface area of nanocatalysts using BET isotherm represented the high surface area for CuO nanosheets and the increase of surface area of nanocomposite in...
Theoretical Study of Adsorption of Organic Pollutants on Polypyrrole with Density Functional Theory (DFT)
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
Phenolic compounds, which are one of the most dangerous compounds for the environment, are present in many effluents of various industries such as petrochemicals and pharmaceuticals, and the need to eliminate these compounds is increasingly felt. In this study, adsorption of three compounds of para-chlorophenol, para-nitrophenol and hydroquinone on polypyrrole adsorbent in the form of neutral, charged, copolymer with polyaniline and phosphorus-doped have been investigated using density functional theory (DFT). Calculations are performed at two levels of b3lyp/6-31+G(d,p) and wb97xd/631+G(d,p) for two different orientations of adsorbate molecules that the correlation-exchange function wb97xd...
Synthesis of Solar Light Responsive Nanocatalysts and Investigation of their Performance in Water Splitting Reaction
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
Today, fossil fuels cause countless environmental pollutants, so replacing fossil fuels with clean energy sources is very important. Water splitting using light and a semiconductor is one of the new methods of producing oxygen and hydrogen, which due to its simplicity and cheapness, has attracted a lot of attention today. In this study, ZnMn2O4 photocatalyst nanoparticles were first loaded on a graphitic carbon nitride support in different ratios of ZnMn2O4 and carbon support by hydrothermal method. Then the photocatalysts were evaluated for evolution of oxygen and hydrogen photocatalysts through water splitting under visible light. In ZnMn2O4 / g-C3N4 (80:20) nanocomposite, the highest...
Theoretical Study of Organic Pollutants Adsorption on Graphene, Doped Graphene and Defective Graphene Nanosheets
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanou (Supervisor)
Abstract
Among the xenobiotic compounds, chlorophenols are considered to be as the most dangerous compounds for the environment and living organisms. These compounds are abundantly found in the wastewater of many chemical industry factories. In this research, by using Gaussian software and density functional theory at the level of B3LYP / 6-31G (d, p),the adsorption of molecules such as phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol over graphene, nitrogen and boron doped graphene sheet are studied. The most stable configurations were determined and adsorption energies were calculated. In addition, to understand the adsorption mechanism, electron properties such as state density and...
Kinetics Investigation of Oxygen Evolution from Water Oxidation in the Presence of Bismuth Vanadate Nanocatalysts
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
In this project, BiVO4 , Mn3O4 and BiVO4- Mn3O4 nanocatalysts were synthesized using the hydrothermal method. The properties of these nanocatalysts were determined by XRD, SEM, FT-IR, DRS, PL, ICP, EDX, BET and AA techniques. Analysys XRD patterns and SEM images of samples confirmed monoclinic structure for BiVO4 and tetragonal structure for Mn3O4. The DRS and PL spectra showed adctrease in the band gap and electron – hole pair recombination for BM 60:40 relative to BiVO4. Oxygen production was studied in the presence of different percentages of BiVO4 and Mn3O4 in BiVO4 - Mn3O4 nanocomposite and was observed that the 60:40 wt.% (Bismuth vanadate 60% and manganese oxide 40%) produced more...
Theoretical Investigation of Basicity and Proton Transfer Energy of Protic Energetic Ionic Liquids in the Gas Phase and in Solution
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
The use of energetic ionic liquids as hypergolic fuels, has low toxicity and environmental risk relative the hypergolic fuels such as the hydrazine. In this research by using Gauss view and Gaussian softwares and density functional theory and MP2 methods at the level of B3LYP/6-311G(d,p), the proton transfer from the cations to anions for a set of hypergolic ionic liquids in the gas and solution phases were studied. The most stable configuration of cations and anions are determined. The interaction energies of the selected cations and anions, proton affinities and basicity properties of these hypergolic anions are calculated. The result represents that the lower proton affinity and basicity...
Kinetics Investigation of the Degradation of Environmental Pollutants by Electro-Fenton Processes Using Iron Vanadate Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
Nanocomposite FeVO4/CeO2 was synthesized by hydrothermal method and was applied for removal of methyl orange. This nanocomposite was characterized by SEM, FT-IR, XRD, BET methods. SEM images showed that FeVO4 nanorode decorated on CeO2 spherical particles. The results of XRD patterns confirmed the triclinic structure for Fe(III)vanadate and the cubic fluorite structure for cerium oxide. The surface area of FeVO4, CeO2 and FeVO4/CeO2 was determined by BET analysis which the results represented an increase in surface area in nanocomposite using cerium oxide as support. The electro-Fenton reaction was performed in undivided electrochemical reactor using stainless steel electrodes and the...
Kinetics Investigation of Environmental Pollutants Degradation in Advanced Oxidation Processes Using Metal Oxide Nanocatalysts
, Ph.D. Dissertation Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
In this project, metal oxides loaded on different supports were used in the heterogeneous electro-Fenton (EF) process for organic pollutants removal. At first, Fe3O4/AC was synthesized for catechol degradation as a phenolic compound. 98.2% removal of catechol was achieved by operational conditions optimization. The catalytic activity of Fe3O4/AC was remained constant after 6 cycles. In the other study, reduced graphene oxide was used as a support for the magnetite nanoparticle catalyst. The catalytic activity of Fe3O4/rGO in EF degradation of reactive red 195 (RR195) dye was studied and 93.34% removal was obtained. Response surface methodology (RSM) was used and a quadratic model with...
Theoretical and Experemental Study of Solid Base Nanocatalysts (Metal Oxides) Modified by Ionic Liquids and Kinetics Investigation of Organic Reactions Such as Hillman and Biodiesel in the Presence of These Nanocatalysts
, Ph.D. Dissertation Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
Thermodynamic quantities such as proton affinity (PA) and molecular basicity (GB) for (CaO)n nanoclusters with n=2–16 have been calculated using three computational models of the DFT (B3LYP, M06, PW91, CAM–B3LYP and ωB97XD functionals), MP2, and HF with the cc-PVNZ (n = D and T) basis set in the gas phase. Absolute deviation error (AAD%) indicates that obtained PA and GB values using DFT model and the B3LYP method with mean percentage errors of 0.77 and 0.90 %, respectively, have the higher accuracy than the other methods and models. Owing to the unique physical and chemical properties of ILs, can be used as catalysts, promoters and modifiers of catalyst in many organic reactions. Therefore,...