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Performance investigation of a four stroke diesel engine, using water-based ferrofluid as an additive
, Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 11 November 2011 through 17 November 2011 ; Volume 4, Issue PARTS A AND B , November , 2011 , Pages 1339-1343 ; 9780791854907 (ISBN) ; Jahani, N ; Shafii, M. B ; ASME ; Sharif University of Technology
2011
Abstract
In this experimental study, a four stroke diesel engine was conducted to investigate the effect of adding water-based ferrofluid to diesel fuel on engine performance. To our knowledge, Magnetic nanoparticles had not been used before. To this end, emulsified diesel fuels of 0, 0.4, and 0.8 water-based ferrofluid/Diesel ratios by volume were used as fuel. The ferrofluid used in this study was a handmade water-based ferrofluid prepared by the authors. The results show that adding water-based ferrofluid to diesel fuel has a perceptible effect on engine performance, increasing the brake thermal efficiency relatively up to 12%, and decreasing the brake specific fuel consumption relatively up to...
Scale invariant feature transform using oriented pattern
, Article Canadian Conference on Electrical and Computer Engineering ; 2014 ; Babaie-Zadeh, M ; Ghorshi, S ; Sharif University of Technology
2014
Abstract
Image matching plays an important role in many aspects of computer vision. Our proposed method is based on Scale Invariant Feature Transform (SIFT) which is one of the popular image matching methods. The main ideas behind our method are removing the excess keypoints, adding oriented patterns to descriptor, and decreasing the size of the descriptors. By doing these changes to SIFT, we would have oriented patterns of keypoints. In addition, the numbers of keypoints have been reduced and the places of keypoints would be selected more accurately, and also the size of the descriptors has been reduced
Investigating Different Crumb Rubber Modification Methods in Cold Mix Asphalts
, M.Sc. Thesis Sharif University of Technology ; Motamed, Arash (Supervisor)
Abstract
Studies have shown that use of crumb rubber additive can improve the mechanical and performance properties of hot mix asphalts. Nowadays, different methods are used for adding crumb rubber to asphalt mixtures. However, no comprehensive research has been done to investigate the effects of these different methods in cold mix asphalts. In this research, different crumb rubber modification methods were evaluated to compare their effects on cold mix asphalts’ performance. In this regard, various crumb rubber modification methods, such as pre blending crumb rubber into the asphalt before emulsification, post blending crumb rubber into the prepared asphalt emulsion and blending crumb rubber with...
, M.Sc. Thesis Sharif University of Technology ; Zohuri Zangeneh, Bijan (Supervisor)
Abstract
Theoretical investigation of stochastic delay differential equation driven by fractional Brownian motion is important issue because of its application in the modeling. In this thesis, after defining of the stochastic integral with respect to fractional Brownian motion and describing the delay differential equation, we prove existence and
uniqueness of solution of stochastic delay differential equation driven by fractional Brownian motion with Hurst parameter H>1/2 and we show that the solution has finite moments from each order. Moreover we show when the delay goes to zero, thesolutions to these equations converge, almost surely and in Lp, to the solution for the equation without delay....
uniqueness of solution of stochastic delay differential equation driven by fractional Brownian motion with Hurst parameter H>1/2 and we show that the solution has finite moments from each order. Moreover we show when the delay goes to zero, thesolutions to these equations converge, almost surely and in Lp, to the solution for the equation without delay....
Improving fracture and moisture resistance of cold mix asphalt (CMA) using crumb rubber and cement
, Article Road Materials and Pavement Design ; 2020 ; Motamed, A ; Imaninasab, R ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Due to environmental and economic advantages, cold mix asphalt (CMA) can be considered as a good alternative to conventional hot mix asphalt (HMA). Nevertheless, it has inferior performance compared to HMA, so that the application of CMA is not recommended in the surface layer of pavements subjected to high traffic volume and/or regions with very cold or hot climate. Considering the high potential of distress occurring in the CMAs, this research is aimed at investigating the effect of crumb rubber (CR) on fracture and moisture damage resistance of the CMAs. Different CR percentages were applied through two different modification methods and, then by means of Semi-Circular Bending (SCB) test,...
Improving fracture and moisture resistance of cold mix asphalt (CMA) using crumb rubber and cement
, Article Road Materials and Pavement Design ; Volume 23, Issue 3 , 2022 , Pages 527-545 ; 14680629 (ISSN) ; Motamed, A ; Imaninasab, R ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
Due to environmental and economic advantages, cold mix asphalt (CMA) can be considered as a good alternative to conventional hot mix asphalt (HMA). Nevertheless, it has inferior performance compared to HMA, so that the application of CMA is not recommended in the surface layer of pavements subjected to high traffic volume and/or regions with very cold or hot climate. Considering the high potential of distress occurring in the CMAs, this research is aimed at investigating the effect of crumb rubber (CR) on fracture and moisture damage resistance of the CMAs. Different CR percentages were applied through two different modification methods and, then by means of Semi-Circular Bending (SCB) test,...
Algebraic Families of Subfields in Division Rings
, M.Sc. Thesis Sharif University of Technology ; Mahdavi Hezavehi, Mohammad (Supervisor)
Abstract
If L is a finite-dimensional Lie algebra over the field F then the universal enveloping algebra U(L) can be embedded in a division ring D. In particular, if L is a solvable p-algebra, there is a decomposition D=KR where K and R are maximal subfields of D, K is Galois extension of the center Z of D and R is a purely inseparable extension of Z with R^p⊆Z. The present thesis is concerned with the compared structures of maximal subfields in a division D and in the division ring of rational functions D(X). We prove that maximal subfields of D(X) “generically” specialize to maximal subfields of D, and properties such as being Galois or purely inseparable over the centre also carry over...
Synthesis and Study of Photocatalytic Activity of Biphasic Titanium Dioxide Loaded with Au@Ag@Au Core Double Shell Bimetallic Nanoparticles
, Ph.D. Dissertation Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
The aim of this project is the synthesis and study of the photocatalytic activity of biphasic titanium dioxide loaded with Au@Ag@Au core double shell bimetallic nanoparticles. The creation of nanostructure, utilization of hierarchical biphasic morphology, loading of light-sensitive particles, and stabilization of photocatalytic particles have enhanced the titanium dioxide photocatalytic activity via approaches of (1) sensitization to visible light, (2) separation of charge carriers produced by light irradiation and minimization of their recombination, and (3) advancing reaction and absorption of reactants by increasing quantity and quality of surface active sites. Hierarchical TiO2...
Photocatalytic activity of rutile/anatase TiO 2 nanorod/nanobranch thin film loaded with Au@Ag@Au core double shell nanoparticles
, Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 380 , 2019 ; 10106030 (ISSN) ; Sadrnezhaad, S. K ; Sharif University of Technology
Elsevier B.V
2019
Abstract
A seeding-growth approach was used to prepare Au@Ag@Au core double shell nanoparticles which were loaded on a rutile-nanorods/anatase-nanobranches thin film via the impregnation method. The thin film was synthesized on a fluorine-doped SnO 2 substrate via three stages of (i)TiCl 4 treatment, (ii)hydrothermal, and (iii)aqueous chemistry. The photocatalytic capability of the newly developed nanostructure was higher than P25 TiO 2 thin film by 40% under visible light and by 100% under UV light irradiation. Photogenerated charges separation at the junctions of rutile-nanorods and anatase-nanobranches along with localized surface plasmon resonance followed by the hot electron transfer from the...
Biphasic TiO2 nanoleafed nanorod electrode for dye-sensitized solar cell
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 123 , 2020 ; Sadrnezhaad, S. K ; Sharif University of Technology
Elsevier B.V
2020
Abstract
The thin-film of hierarchical rutile/anatase TiO2 nanorod/nanoleafs on fluorine-doped tin oxide glass was prepared via a facile method. For this purpose, the hydrothermal method was used for the synthesis of rutile-phase nanorods on the TiO2 seeded FTO, and aqueous chemistry was applied for growing anatase-phase nanoleafs on the nanorods. The structural, morphological, and optical properties of coating characterized, and the thin-film utilized as the photoelectrode for dye-sensitized solar cell. The energy conversion efficiency of the newly developed nanostructure was higher than that of TiO2 nanorod thin-film by 40%. This increase could be ascribed to: (1) superior specific surface area...
Anionic and cationic pollutants degradation via TiO2 nanoleafed nanorods
, Article Solid State Sciences ; Volume 105 , 2020 ; Sadrnezhaad, S. K ; Sharif University of Technology
Elsevier Masson SAS
2020
Abstract
Hierarchical TiO2 nanoleafed nanorod thin film was successfully synthesized on the fluorine doped tin oxide glass substrate. For this purpose, the nanorods were coated on the TiO2 seeded substrate via the hydrothermal method. Then, nanoleafs were grown on the nanorods by aqueous chemistry. Field emission scanning electron microscopy, energy dispersive spectroscopy, and Raman spectroscopy were utilized for thin film characterization. The results clarified that anatase-phase nanoleafs were uniformly grown on the rutile-phase nanorods in the TiO2 coating. The photocatalytic performance of the thin film was determined by photodegradation of anionic and cationic organic pollutants, and the...
Gold@Silver@Gold Core double-shell nanoparticles: synthesis and aggregation-enhanced two-photon photoluminescence evaluation
, Article Plasmonics ; Volume 15, Issue 2 , 2020 , Pages 409-416 ; Sadrnezhaad, S. K ; Sharif University of Technology
Springer
2020
Abstract
A facile, straightforward, and low-cost method is proposed to synthesize gold@silver@gold core double-shell nanoparticles. The technique is a seed-mediated growth protocol that contains four steps of (1) gold seed synthesis, (2) gold seed growth, (3) silver layer coating through silver salt reduction, and (4) gold layer deposition via gold precursor reduction. The prepared nanoparticles had a narrow size distribution and the average particle size of 28 ± 1 nm. Cysteine was introduced to the nanoparticles solution as a coupling agent to assemble nanoparticles. Aggregation-induced two-photon photoluminescence enhancement of three types assembled nanoparticles, i.e., gold@silver@gold,...
Hierarchical rutile/anatase TiO 2 nanorod/nanoflower thin film: Synthesis and characterizations
, Article Materials Science in Semiconductor Processing ; Volume 93 , 2019 , Pages 252-259 ; 13698001 (ISSN) ; Eslami Saed, A ; Sadrnezhaad, S. K ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Hierarchical TiO 2 nanorod/nanoflower thin film was synthesized on fluorine doped tin oxide glass via hydrothermal and aqueous chemistry methods. According to field emission scanning electron microscopy results, the thin film was crack-free and uniform. Primary nanorods had an average diameter of 95 nm and a length of 2 µm. They were perpendicular to the substrate owing to the TiO 2 prenucleation. Growth of the nanoflowers on the nanorods could increase both the specific surface area and roughness. X-ray diffraction and Raman spectroscopy showed that the nanorods were rutile; while the nanoflowers were anatase. Efficient electron transfer from anatase to rutile could therefore occur....
K-Strong Conflict Free Coloring of Regions with Respect to a Family of Points
, M.Sc. Thesis Sharif University of Technology ; Abam, Mohammad Ali (Supervisor)
Abstract
The conflict-free coloring is one of the computational geometry problems that has received attention in the last two decades. The root of this problem comes from the frequency allocation problem to telecommunications antennas, where we have several telecommunication antennas in two-dimensional space aiming to assign to each of them a frequency so that every point on the plane, which is at least inside one of the antenna ranges, stays in a range with a frequency different from the other antennas containing point.One of the generalizations of this problem is the k-strong case, where we have n regions (equivalent to the circular region of the antennas) that we want to color so that for each...
Designing and Implementing an Enhanced Classification Algorithm in Image Processing
, M.Sc. Thesis Sharif University of Technology ; Babaie-zadeh, Massoud (Supervisor) ; Ghorshi, Alireza (Co-Advisor)
Abstract
Statistical learning plays a key role in many areas of science [38]. An example of learning problems is image matching, image matching plays an important role in many aspects of computer vision.Computers can be used in intelligent tasks, which are followed by logical inference, for example, visual scenes (images or videos) or speech (audios). For humans visual system of such task are performed hundreds of times every day so easily sometimes without any awareness. In this thesis we focus on the image matching phase which is the first phase of the classification process. One of the popular image matching methods is Scale Invariant Feature Transform (SIFT) which our proposed method is based on...
Performance Investigation of a Diesel Engine Using Nano Particles
,
M.Sc. Thesis
Sharif University of Technology
;
Shafii, Mohammad Behshad
(Supervisor)
;
Saboohi, Yadollah
(Supervisor)
;
Mobini, Kamran
(Supervisor)
Abstract
In this Study, experimental tests were carried out to investigate the effects of adding water-based ferrofluid to diesel fuel in a diesel engine. These effects included the combustion performance and exhaust emission characteristics of the diesel engine. To this end, emulsified diesel fuels of 0, 0.4, and 0.8 ferrofluid/Diesel ratios by volume were used in a four stroke diesel engine. The results indicate that adding ferrofluid to diesel fuel has a perceptible effect on engine performance, increasing the brake thermal efficiency and decreasing the brake specific fuel consumption as compared to diesel fuel. Furthermore, adding ferrofluid to diesel fuel increased the exhaust gaseous...
BF3·SiO2: an efficient reagent system for the one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles
, Article Tetrahedron Letters ; Volume 49, Issue 16 , 2008 , Pages 2575-2577 ; 00404039 (ISSN) ; Mirjalili, B. B. F ; Hashemi, M. M ; Sharif University of Technology
2008
Abstract
Silica-supported boron trifluoride (BF3·SiO2) is an efficient, readily available and reusable catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles using benzil, an aromatic aldehyde and an amine in the presence of ammonium acetate. This one-pot procedure is very simple, affording good to excellent yields. © 2008 Elsevier Ltd. All rights reserved
Application of Bhattacharyya distance as a dissimilarity index for automated prediction of epileptic seizures in rats
, Article 2010 International Conference on Intelligent and Advanced Systems, ICIAS 2010, 15 June 2010 through 17 June 2010 ; 2010 ; 9781424466238 (ISBN) ; Vosoughi Vahdat, B ; Shamsollahi, M. B ; Sayyah, M ; Sharif University of Technology
2010
Abstract
Seizures are defined as manifest of excessive and hypersynchronous activity of neurons in the cerebral cortex and represent a frequent malfunction of the human central nervous system. Therefore, the search for precursors and predictors of a seizure is of utmost clinical relevance and may even guide us to a deep understanding of the seizure generating mechanisms. In this study we analyzed invasive electroencephalogram (EEG) recordings in rats with experimentally induced generalized epilepsy with a nonlinear method called, dissimilarity index. In order to predict epileptic seizures automatically, Bhattacharyya distance between trajectory matrix of reference window, during an interval quite...
Correlation for Nusselt number in pure magnetic convection ferrofluid flow in a square cavity by a numerical investigation
, Article Journal of Magnetism and Magnetic Materials ; Volume 322, Issue 22 , November , 2010 , Pages 3607-3613 ; 03048853 (ISSN) ; Ebrahimi, B ; Shafii, M. B ; Saidi, M. H ; Saidi, M. S ; Sharif University of Technology
2010
Abstract
Magnetic convection heat transfer in a two-dimensional square cavity induced by magnetic field gradient is investigated numerically using a semi-implicit finite volume method. The side walls of the cavity are heated with different temperatures, the top and bottom walls are isolated, and a permanent magnet is located near the bottom wall. Thermal buoyancy-induced flow is neglected due to the nongravity condition on the plane of the cavity. Conditions for the different values of non-dimensional variables in a variety of ferrofluid properties and magnetic field parameters are studied. Based on this numerical analysis, a general correlation for the overall Nusselt number on the side walls is...
Fetal electrocardiogram R-peak detection using robust tensor decomposition and extended Kalman filtering
, Article Computing in Cardiology ; Volume 40 , 2013 , Pages 189-192 ; 23258861 (ISSN) ; 9781479908844 (ISBN) ; Niknazar, M ; Jutten, C ; Shamsollahi, M. B ; Rivet, B ; Sharif University of Technology
2013
Abstract
In this paper, we propose an efficient method for R-peak detection in noninvasive fetal electrocardiogram (ECG) signals which are acquired from multiple electrodes on mother's abdomen. The proposed method is performed in two steps: first, we employ a robust tensor decomposition-based method for fetal ECG extraction, assuming different heart rates for mother and fetal ECG; then a method based on extended Kalman filter (EKF) in which the ECG beat is modeled by 3 state equations (P, QRS and T), is used for fetal R-peak detection. The results show that the proposed method is efficiently able to estimate the location of R-peaks of fetal ECG signals. The obtained average scores of event 4 and 5 on...