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Quantum chemical parameters of some organic corrosion inhibitors, pyridine, 2-picoline 4-picoline and 2,4-lutidine, adsorption at aluminum surface in hydrocholoric and nitric acids and comparison between two acidic media
, Article Main Group Metal Chemistry ; Volume 26, Issue 6 , 2003 , Pages 349-361 ; 07921241 (ISSN) ; Mollaamin, F ; Gholami, M. R ; Yoosbashizadeh, H ; Sadrnezhad, S.K ; Passdar, H ; Sharif University of Technology
Walter de Gruyter GmbH
2003
Abstract
The effect of new corrosion inhibitors, namely pyridine, 2-methylpyridine (2-picoline), 4-methylpyridine (4-picoline), 2,4-dimethylpyridine (2,4-lutidine), on the corrosion of Al-surface in hydrocholoric acid (HCl) and nitric acid (HNO3) was investigated at the HF and B3LYP level using the ab initio 6-3IG and LANL2DZ basis sets from the program package Gaussian 98 (A.7 Public Domain version). The physico-chemical properties of corrosion inhibitors are one of the principal criteria for the determination and selection of inhibitors. The inhibition of the Al-surface in solutions of hydrocholoric acid and nitric acid by some N-heterocyclic compounds has been studied. The calculated results...
Estimating a Surface Registration Technique Using Surface Modeling Method
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Saadat, Mahmood (Supervisor)
Abstract
Due to enhancements in medical world, some medical instruments have been developed in order to assist surgeons. Navigation systems as one of the progressive ones make a virtual environment to simplify the surgeons. Three-dimensional registration is a necessary step through these systems and widely used in shape analysis, surface representation, and medical image-aided surgery. In addition, It’s relevance to medical imaging is that there is much useful anatomical information in the form of collected surface points which originate from complimentary modalities. In this study, the kinematic relations between two point clouds with different coordinate definitions have been generated. Using...
Surface modeling of complicated geometries with incomplete erroneous data points- An extension to B-spline approach
, Article 2005 27th Annual International Conference of the Engineering in Medicine and Biology Society, IEEE-EMBS 2005, Shanghai, 1 September 2005 through 4 September 2005 ; Volume 7 VOLS , 2005 , Pages 1634-1637 ; 05891019 (ISSN); 0780387406 (ISBN); 9780780387409 (ISBN) ; Farahmand, F ; Meghdari, A ; Sharif University of Technology
2005
Abstract
Based on the analogy between the B-spline curve modeling and the force-deflection behavior of a beam subjected to lateral point loads, an extension to the B-spline surface modeling method was introduced. The proposed method has strong extrapolating capability and can develop accurate surface models over an incomplete net of data points without affecting the original data. Extrapolation of the incomplete part of the data net Is conducted simultaneously with interpolation of the existing part, with no need to recalculation. Approximation or data smoothing is a natural extension of the method, however, the smoothing intensity can be controlled continuously without reducing the number of spline...
Response surface analysis of photocatalytic degradation of methyl tert-butyl ether by core/shell Fe3O4/ZnO nanoparticles
, Article Journal of Environmental Health Science and Engineering ; Vol. 12, issue. 1 , 2014 ; Rostami, M. H ; Alizadeh, M ; Alizadehbirjandi, A ; Nakhli, S. A. A ; Aminzadeh, R ; Sharif University of Technology
Abstract
The degradation of methyl tert-butyl ether (MTBE) was investigated in the aqueous solution of coated ZnO onto magnetite nanoparticale based on an advanced photocatalytic oxidation process. The photocatalysts were synthesized by coating of ZnO onto magnetite using precipitation method. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibration sample magnetometer (VSM). Besides, specific surface area was also determined by BET method. The four effective factors including pH of the reaction mixture, Fe3O4/ZnO magnetic nanoparticles concentration, initial MTBE concentration and molar ratio of [H2O2]/ [MTBE] were optimized using response surface...
Tracking the 3D configuration of human joint using an MR image registration technique
, Article ASME 2010 5th Frontiers in Biomedical Devices Conference and Exhibition, BIOMED 2010, 20 September 2010 through 21 September 2010 ; 2010 , Pages 93-94 ; 9780791849453 (ISBN) ; Farahmand, F ; Jafari, A ; Sharif University of Technology
Abstract
Surface registration is a necessary step and widely used in medical image-aided surgery. It's relevance to medical imaging is that there is much useful anatomical information in the form of collected surface points which originate from complimentary modalities. In this study, the kinematic relations between two point clouds with different coordinate definitions have been generated. Using Influence Method of surface modeling for extracting point clouds functions, the transformation matrix would be resulted. The proposed method was applied for an experimental femur data points(651 points) using the MRI images. These data points were transformed in a 30 degrees flexion of knee. This...
Numerical Simulation of Free Surface Flows Using Unstructured Grids
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor) ; Nouri Borujerdi, Ali (Supervisor)
Abstract
The Present Study Deals With The Numerical Modeling Of Free Surface Flows Using Unstructured Grids, That Is An Extension Of Later Studies At Research Institute Of Marine Engineering With The Goal Of Developing A Robust CFD Code. One Of The Most Applicable Aspects Of This Software Is Simulation Of Ship Maneuver And Calculation Of Hydrodynamic Resistance Of Floating Structures That Arises From Combination Of Equations Governing The Flow And 6DOF Rigid Body Equations. This Study Represents Some Proposed Algorithms For Solving Navier-Stokes Equations, Volume Fraction Equation And Rigid Body Equations In A Time Marching Manner. These Equations Are Discretized Based On A Collocated Arrangement For...
Comparison and Improving of Free Surface Modeling Methods In Moving Grids
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor) ; Nouri Borujerdi, Ali (Supervisor)
Abstract
In the present study a through comparison has been made between different free surface modeling methods. Methods for improving the current schemes are analyzed and studied. Among different proposed methods and based on the current in-house CFD solver’s limitations and capabilities, the Flux-Blending Strategy has been used for interface capturing in the framework of the Finite Volume Method (FVM). The proposed scheme has been coupled with other algorithms for improving the capabilities and functionality of the general computational fluid dynamic software, NUMELS, in order to simulate fluid flows with sharp interface.
The improved interface capturing scheme uses the continuous switching...
The improved interface capturing scheme uses the continuous switching...
Direct pore-scale modeling of two-phase flow: investigation of the effect of interfacial tension and contact angle
, Article Special Topics and Reviews in Porous Media ; Volume 12, Issue 3 , 2021 , Pages 71-88 ; 21514798 (ISSN) ; Hashemabadi, S. H ; Alamooti, A. H. M ; Sharif University of Technology
Begell House Inc
2021
Abstract
The process of fluid flow displacement in porous media has recently gained great prominence owing to its widespread usage in a variety of industries, especially in the case of pore scale investigations. Although, many studies have been conducted to address pore-scale investigations in both modeling and experimental approaches, the role of interfacial tension and contact angle on pore-scale phenomena is less focused. In this work, direct pore-scale modeling was used to precisely examine the effect of interfacial tension and contact angle on the fluid flow at the microscale. Also, several pore-scale mechanisms, including Haines jump and dynamic breakup mechanisms, were observed. Therefore, the...
Quantifying the impacts of agricultural alteration and climate change on the water cycle dynamics in a headwater catchment of Lake Urmia Basin
, Article Agricultural Water Management ; Volume 270 , 2022 ; 03783774 (ISSN) ; Danesh Yazdi, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
The rapid shrinkage of Lake Urmia over the past two decades has raised serious environmental concerns. Several restoration plans have been proposed to reduce agricultural water consumption to supply a remarkable fraction of the lake's environmental flow requirement. However, an accurate and realistic evaluation of the effectiveness of these plans in reducing agricultural water consumption across the basin is still poorly understood. This study assessed the water-saving potential of agricultural alteration in a snow-dominated catchment in the Lake Urmia Basin. In particular, we explored the impact of crop pattern alteration via reducing the cultivation area and employing different irrigation...
2D numerical simulation of density currents using the SPH projection method
, Article European Journal of Mechanics, B/Fluids ; Volume 38 , 2013 , Pages 38-46 ; 09977546 (ISSN) ; Firoozabadi, B ; Mahdinia, M ; Sharif University of Technology
2013
Abstract
Density currents (DCs) or gravity currents are driven by gravity in a fluid environment with density variation. Smoothed Particle Hydrodynamics (SPH) has been proved to have capabilities such as free surface modeling and accurate tracking of the immiscible-fluids interface that can be useful in the context of gravity currents. However, SPH applications to gravity currents have been limited to often-coarse simulations of high density-ratio currents. In this work, the SPH projection method is tried to solve currents with very low density-ratios (close to one), at a resolution, that captures the Kelvin-Helmholtz instabilities at the fluids interface. Existing implementations of the SPH...
SAMA-VTOL: A new unmanned aircraft system for remotely sensed data collection
, Article SPIE Future Sensing Technologies 2020, 9 November 2020 through 13 November 2020 ; Volume 11525 , 2020 ; Khoshboresh Masouleh, M ; The Society of Photo-Optical Instrumentation Engineers (SPIE) ; Sharif University of Technology
SPIE
2020
Abstract
In recent years, unmanned aircraft systems (UASs) are frequently used in many different applications of photogrammetry such as building damage monitoring, archaeological mapping and vegetation monitoring. In this paper, a new vertical take-off and landing fixed-wing UAS is proposed to robust photogrammetry missions, called SAMA-VTOL. In this study, the capability of SAMA-VTOL is investigated for generating orthophoto. The major stages are including designing, building and experimental scenario. First, a brief description of design and build is introduced. Next, an experiment was done to generate accurate orthophoto with minimum ground control points requirements. The processing step, which...
A new approach to C2 continuous piecewise bicubic representation of the articular surfaces of diarthrodial joints
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 220, Issue 4 , 2006 , Pages 553-563 ; 09544119 (ISSN) ; Farahmand, F ; Meghdari, A ; Golestanha, A. S ; Sharif University of Technology
2006
Abstract
Based on the force-deflection equation for a beam subjected to lateral point loads, a C2 continuous piecewise bicubic mathematical representation was proposed to model complicated geometrical surfaces, e.g. the articular surfaces of human joints. The method was then extended so that it could be used for mathematical modelling of incomplete nets of data points, as well as smoothing of noisy and/or filtering of erroneous data points. Mathematical techniques were also developed to calculate the required unknown parameters explicitly, with no need to solve the system of equations simultaneously. The performance of the proposed method was evaluated on a number of surface modelling problems,...