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Application of a continuous kinetic model for the hydrocracking of vacuum gas oil
, Article Petroleum Science and Technology ; Vol. 32, Issue. 18 , 2014 , Pages 2245-2252 ; ISSN: 10916466 ; Khorasheh, F ; Farhadi, F ; Sharif University of Technology
2014
Abstract
Hydrocracking is one of the most versatile petroleum refining processes for production of valuable products including gasoline, gas oil, and jet fuel. In this paper, a five-parameter continuous lumping model was used for kinetic modeling of hydrocracking of vacuum gas oil (VGO). The model parameters were estimated from industrial data obtained from a fixed bed reactor operating at an average temperature of 400°C and residence time of 0.3 h. Product distributions were obtained in terms of the weight fraction of various boiling point cuts. The model parameters were estimated using the Nelder-Mead optimization procedure and were correlated with temperature. Comparison of experimental and...
Video Instance Segmentation via Spatio-temporal Embedding and Clustering
, Ph.D. Dissertation Sharif University of Technology ; Kasaei, Shohreh (Supervisor)
Abstract
Video Instance Segmentation is one of the newest tasks in computer vision, tasked with segmenting, categorizing, and tracking instances across video frames. This task is highly significant and applicable today in industries such as autonomous vehicles, surveillance systems, production lines, and medical video analysis. Generally, there are two approaches for solving the task of Video Instance Segmentation: the object-oriented approach and the pixel-oriented approach. In the object-oriented approach, after detecting instances at the image level, the segmentation and tracking processes are performed to link the instances. In the pixel-oriented approach, all spatial-temporal information is...
Providing Optimization Tools to Design Aeroelastic Blades of Wind Turbines Made of Curved Fibers
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
Nowadays Aeroelasticity is one of most important branch of aerospace science. The Aeroelastic analysis and get on aeroelastic safety margin, is one of the major steps that must be taken in flying crafts design. Diverse software have been developed for this purpose. Due to the increasing the demands of use of composite materials in aircraft structures, need to examine the effect of various parameters such as angles and stacking sequence on the aeroelastic instability (flutter and divergence) composite aircraft structures is determined. The analysis of wind turbines as a means of extracting energy from the wind and having a large diameter blades, causing the interference effects of aerodynamic...
A Novel Loss Function Based on Clustering Quality Criteria in Spatio-Temporal Clustering
, Article Iranian Conference on Machine Vision and Image Processing, MVIP ; 2024 ; 21666776 (ISSN); 979-835035049-4 (ISBN) ; Ramezanian, V ; Kasaei, S ; Sharif University of Technology
2024
Abstract
Video instance segmentation has diverse applications in the autonomous vehicle industry, image surveillance systems, production lines, and medical video analysis. There are two approaches, top-down and bottom-up, to address the task of instance segmentation in video. Top-down methods heavily rely on image-level segmentation and have separate processes for detection and tracking. They show a strong dependency on image-level segmentation. Bottom-up approaches leverage both spatial and temporal information simultaneously, aiming for a gradual transition from pixel-level features to spatiotemporal instances. This paper introduces a novel method to improve the performance of video instance...
Improving the Efficiency of Federated Learning in Resource Allocation for Heterogeneous Networks through Intentional Client Selection
, M.Sc. Thesis Sharif University of Technology ; Safaei, Bardia (Supervisor)
Abstract
The rapid expansion of the Internet of Medical Things (IoMT) and the massive generation of multimodal health data have provided unprecedented opportunities for early disease diagnosis and smart patient monitoring. However, the effective utilization of these data faces fundamental challenges regarding privacy preservation and severe computational resource constraints on edge devices. The distributed approach of Federated Learning (FL) addresses privacy concerns by training models locally without transferring raw data. Nevertheless, its implementation in real-world environments suffers from performance degradation due to device heterogeneity (the straggler effect) and their inability to run...
Method of Implementation of MSG-3 for Boeing 747
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Many airlines operate different fleets under different service conditions. These aircraft fleets need to be maintained in service. Safety, reliability and economic reasons motivate manufacturers, airlines and airworthiness authorities to investigate about different approaches to aircraft maintenance. At first, corrective maintenance which was developed for other industries was used by the aircraft industry but due to increasing complexity of aircrafts and their systems the industry started using time based maintenance. After years of operation and fleet experience, this industry started developing a program of its own i.e., MSG-1, MSG-2 and MSG-3. These maintenance programs have been evolved...
Deep spectral improvement for unsupervised image instance segmentation
, Article PLoS ONE ; Volume 19, Issue 10 October , 2024 ; 19326203 (ISSN) ; Mansourian, A. M ; Kasaei, S ; Sharif University of Technology
2024
Abstract
Recently, there has been growing interest in deep spectral methods for image localization and segmentation, influenced by traditional spectral segmentation approaches. These methods reframe the image decomposition process as a graph partitioning task by extracting features using self-supervised learning and utilizing the Laplacian of the affinity matrix to obtain eigensegments. However, instance segmentation has received less attention than other tasks within the context of deep spectral methods. This paper addresses that not all channels of the feature map extracted from a self-supervised backbone contain sufficient information for instance segmentation purposes. Some channels are noisy and...
Substitutional doping of Cu in diamond: Mott physics with p orbitals
, Article European Physical Journal B ; Volume 77, Issue 3 , October , 2010 , Pages 331-336 ; 14346028 (ISSN) ; Jafari, S. A ; Abolhassani, M. R ; Sharif University of Technology
2010
Abstract
Discovery of superconductivity in the impurity band formed by heavy doping of boron into diamond (C:B) as well as doping of boron into silicon (Si:B) has provided a rout for the possibility of new families of superconducting materials. Motivated by the special role played by copper atoms in high temperature superconducting materials where essentially Cu d orbitals are responsible for a variety of correlation induced phases, in this paper we investigate the effect of substitutional doping of Cu into diamond. Our extensive first principle calculations based on density functional theory which are averaged over various geometries indicate the formation of a mid-gap band, which mainly arises from...
A mild and chemoselective dithioacetalization of aldehydes in the presence of anhydrous copper (II) sulfate
, Article Phosphorus, Sulfur and Silicon and the Related Elements ; Volume 181, Issue 6 , 2006 , Pages 1445-1450 ; 10426507 (ISSN) ; Rezanejade Bardajee , G ; Arefi Oskui , A ; Sharif University of Technology
2006
Abstract
Various aldehydes have been protected with different thiols as dithioacetals with excellent yields using anhydrous copper sulfate as a mild and chemoselective catalyst. The reaction is carried out in a solvent and/or under solvent-free conditions. The transthioacetalization of oxyacetals into dithioacetals was also achieved in an excellent yield. Copyright © Taylor & Francis Group, LLC
Development of a Continuous Lumping Model for Kinetic Modeling of The Isomax Reactors
, M.Sc. Thesis Sharif University of Technology ; Khorasheh, Farhad (Supervisor) ; Farhadi, Fathollah (Supervisor)
Abstract
Hydrocracking is one of the most versatile petroleum refining process for production of valuable products including gasoline, gas oil, and kerosene. Various kinetic models have been proposed for hydrocracking process. A commonly used approach is to consider the mixture in terms of selected lums, which can be specified in terms of structural characteristics, such as boiling point. From this approach the reaction mixture can be considered in two types of discrete lumping and continuous lumping. In this thesis, a 5 parameter continuous kinetic lumping model was studied for modeling of the Isomax reactor of Tabriz refinery whose feedstock is a low quality gasoil from vaccum distillatin column....
Fabrication and Characterization of the Buffer Layer and Interface with Absorbent Layer in Chalcopyrite Solar Cells Thin Layers by Solubility-Based Methods
, M.Sc. Thesis Sharif University of Technology ; Taghavinia, Nima (Supervisor) ; Dehghani, Mehdi (Supervisor)
Abstract
In this research, the first attempt was made to increase the thickness of the absorbent layer and increase the size of the absorbent layer crystals and minimize the cavities of this layer. this attempt resulted in the synthesis of absorbent layer with a thickness of about one micrometer and with low cavities. then, an attempt was made to crystallize the buffer layer and form the bond with the absorbent layer. these efforts led to the synthesis of a cadmium sulfide layer with a high carrier density. in this study, cadmium sulfide and cadmium zinc sulfide and indium sulfide were used to make the cell. then we could synthesizing window layer with low resistance.at end, we made superstrate...
Design of an optimal robust position controller for IPMSM
, Article UPEC 2002, 37th International Universities' Power Engineering Conference, Stafford, 9 September 2002 through 11 September 2002 ; Volume 37 , 2002 , Pages 693-697 ; Abdi J, E ; Zolghadri, M. R ; Oraee, H ; Sharif University of Technology
2002
Abstract
In this paper, the performance of a fuzzy position controller for an interior permanent magnet synchronous motor for robotic applications is investigated. A fuzzy logic controller is employed as an outer position loop. Moreover, a PI controller is employed as an inner speed control loop. The control scheme can be used for both position and speed control applications by enabling and disabling the position controller. Simulation results with Matlab Simulink package are presented. They show that the fuzzy controller is robust, that is, it has low sensitivity to parameter variations and high capability of disturbance rejection
NMR based metabonomics study on celiac disease in the blood serum
, Article Gastroenterology and Hepatology from Bed to Bench ; Volume 6, Issue 4 , 2013 , Pages 190-194 ; 20082258 (ISSN) ; Ektefa, F ; Arefi Oskouie, A ; Rostami, K ; Rezaei Tavirani, M ; Mohammad Alizadeh, A. H ; Tafazzoli, M ; Rostami Nejad, M ; Sharif University of Technology
2013
Abstract
Aim: The aim of this study is to look for the proper methods that would be a major step towards untreated CD diagnosis and seek the metabolic biomarkers causes of CD and compare them to control group. Background: Celiac disease (CD) is a common autoimmune disorder that is not easily diagnosed using the clinical tests. Patients and methods: Thirty cases and 30 controls were entered into this study. Metabolic profiling was obtained using proton nuclear magnetic resonance spectroscopy (1HNMR) to seek metabolites that are helpful for the detection of CD. Classification of CD and healthy subject was done using random forest (RF). Results: The obtained classification model showed an 89% correct...
Conference room reverberation time correction using helmholtz resonators lined with absorbers
, Article Shock and Vibration ; Vol. 2014, issue , May , 2014 ; Ghiasi, S. M. A ; Ghaffari, S. M ; Ramezanghorbani, F ; Sharifpour, S ; Irajizad, P ; Ghoreishi Langroudi, S. D ; Amjadi, A ; Sharif University of Technology
2014
Abstract
Echo and sound resonance in a conference room cause obscure speech and make listeners tired. Thus, the acoustical properties of a conference room are vitally important. The conference room 412 at Sharif University Physics Department failed to meet basic acoustical standards. The aim of this research is to improve reverberation time (RT) of the conference room using Helmholtz resonators with defined dimensions, diffusers, and sound absorbers. Helmholtz resonators are widely used to absorb sound noise especially at low frequencies. They are particularly useful when noise has a narrow-frequency band. One of the advantages of using Helmholtz resonators is their capacity to be tuned on different...
NMR- and GC/MS-based metabolomics of sulfur mustard exposed individuals: a pilot study
, Article Biomarkers ; Volume 21, Issue 6 , 2016 , Pages 479-489 ; 1354750X (ISSN) ; Aliannejad, R ; Rezaei Tavirani, M ; Arefi Oskouie, A ; Naseri, M. T ; Parastar, H ; Aliakbarzadeh, G ; Fathi, F ; Taheri, S ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
Sulfur Mustard (SM) is a potent alkylating agent and its effects on cells and tissues are varied and complex. Due to limitations in the diagnostics of sulfur mustard exposed individuals (SMEIs) by noninvasive approaches, there is a great necessity to develop novel techniques and biomarkers for this condition. We present here the first nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC/MS) metabolic profiling of serum from and healthy controls to identify novel biomarkers in blood serum for better diagnostics. Of note, SMEIs were exposed to SM 30 years ago and that differences between two groups could still be found. Pathways in which differences between SMEIs and...
1H NMR based metabolic profiling in Crohn's disease by random forest methodology
, Article Magnetic Resonance in Chemistry ; Vol. 52, issue. 7 , July , 2014 , p. 370-376 ; Majari-Kasmaee, L ; Mani-Varnosfaderani, A ; Kyani, A ; Rostami-Nejad, M ; Sohrabzadeh, K ; Naderi, N ; Zali, M. R ; Rezaei-Tavirani, M ; Tafazzoli, M ; Arefi-Oskouie, A ; Sharif University of Technology
2014
Abstract
The present study was designed to search for metabolic biomarkers and their correlation with serum zinc in Crohn's disease patients. Crohn's disease (CD) is a form of inflammatory bowel disease that may affect any part of the gastrointestinal tract and can be difficult to diagnose using the clinical tests. Thus, introduction of a novel diagnostic method would be a major step towards CD treatment.Proton nuclear magnetic resonance spectroscopy ( 1H NMR) was employed for metabolic profiling to find out which metabolites in the serum have meaningful significance in the diagnosis of CD. CD and healthy subjects were correctly classified using random forest methodology. The classification model for...
Effect of heating profile on desorption curve in temperature programmed desorption analysis: Case study of acid sites distribution of SAPO-34
, Article Journal of Porous Materials ; Volume 16, Issue 5 , 2009 , Pages 599-603 ; 13802224 (ISSN) ; Farhadi, F ; Khorasheh, F ; Yan, Z. F ; Sharif University of Technology
2009
Abstract
Comparison of the traditional linear heating method of TPD with an original stepwise heating scheme was reported for the first time. Stepwise heating TPD was carried out by keeping the temperature constant as soon as ammonia desorption signal rises until the signal returns to the baseline. More ammonia desorption peaks on a SAPO-34 catalyst were identified using TPD with stepwise heating. The effect of temperature ramp on desorption peak broadening in TPD curve was also addressed. The more distinct ammonia desorption peaks in stepwise TPD indicates that ammonia adsorbs in about five or six different ways on SAPO-34, and attribution of different adsorptions may be explained considering some...
Theoretical and experimental study of cascade solar stills
, Article Solar Energy ; Volume 90 , April , 2013 , Pages 205-211 ; 0038092X (ISSN) ; Sharak, A. Z ; Moghadam, H ; Tabrizi, F. F ; Sharif University of Technology
2013
Abstract
Most part of Iran is dominated by arid and semi-arid areas due to low annual rainfall. The need for production of fresh water from brackish water is considerably high, especially in dry regions. In this study 1 month daily-based experimental data from a solar still site has been reported. The technical and operational problems of this site which finally contributed to the total cease of the site are described. Then a detailed analysis is investigated on progress of a prototype which constructed in order to solve the site's problems. The results of 1 month of experimental data of the final design showed that the last prototype could be used to solve the current problems of the site. The...
An improved methodology for design of custom-made hip prostheses to be fabricated using additive manufacturing technologies
, Article Rapid Prototyping Journal ; Volume 18, Issue 5 , 2012 , Pages 389-400 ; 13552546 (ISSN) ; Abbaszadeh, F ; Farahmand, F ; Sharif University of Technology
Emerald
2012
Abstract
Purpose - The purpose of this paper is to present an improved methodology for design of custom-made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies. Design/methodology/approach - The proposed methodology for design of custom-made hip prostheses is based on an independent design criterion for each of the intra-medullary and extra-medullary portions of the prosthesis. The intra-medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra-medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance...
Evaluation and enhancing of operational performance and training objective in accordance with Line Operations Safety Audit (LOSA)
, Article International Air Safety Seminar Proceedings, 1 November 2011 through 3 November 2011 ; November , 2011 , Pages 78-99 ; 02705176 (ISSN) ; 9781618393975 (ISBN) ; Goodarzi, F ; Sharafbafi, F ; Sharif University of Technology
2011