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    Synergistic effect of MEHPA on co-extraction of zinc and cadmium with DEHPA

    , Article Minerals Engineering ; Volume 17, Issue 1 , 2004 , Pages 89-92 ; 08926875 (ISSN) Keshavarz Alamdari, E ; Moradkhani, D ; Darvishi, D ; Askari, M ; Behnian, D ; Sharif University of Technology
    2004
    Abstract
    Simultaneous extraction of zinc and cadmium by a mixture of di-2-ethyl hexyl phosphoric acid (DEHPA) and mono-2-ethyl hexyl phosphoric acid (MEHPA), and the synergistic effect of MEHPA on co-extraction of zinc and cadmium with DEHPA have been investigated. It was shown that the extraction of zinc and cadmium by DEHPA and/or MEHPA can be increased by an increase of pH. The results also illustrate that the pH0.5 of zinc, by increase in MEHPA from 0.1 to 8 vol%, did not vary significantly while that of cadmium varies from 0.63 to 2.4. In other words MEHPA prevents selective extraction of zinc from aqueous media containing both zinc and cadmium. Studies on the selective separation parameter... 

    Extraction of ZN, MN and CO from ZN-MN-CO-CD-NI containing solution using D2EHPA, Cyanex® 272 and Cyanex® 302

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 24, Issue 2 , 2011 , Pages 183-192 ; 1728-144X (ISSN) Darvishi, D ; Haghshenas, D. F ; Alamdari, E. K ; Sadrnezhaad, S. K ; Sharif University of Technology
    2011
    Abstract
    Effects of pH, D2EHPA, Cyanex® 272 and Cyanex® 302 on extraction of zinc, manganese and cobalt from a Zn-Mn-Co-Cd-Ni containing solution at the room temperature was comprehensively investigated. Addition of Cyanex® 302 indicated a left-shifting-effect on the extraction curve of zinc, a right-shifting-effect on the extraction curve of manganese and no effect on the extraction of cobalt. Addition of Cyanex® 272 shifted all three curves to the right. Therefore, the most suitable extractant for separation of zinc from manganese was therefore 0.3-0.3 mixture of D2EHPA and Cyanex® 302, and that for separation of manganese from cobalt was pure D2EHPA. The stoichiometric coefficient for the... 

    Thermodynamics of vanadium (V) solvent extraction by mixture of D2EHPA and TBP

    , Article International Journal of Mineral Processing ; Volume 138 , May , 2015 , Pages 49-54 ; 03017516 (ISSN) Cheraghi, A ; Ardakani, M. S ; Keshavarz Alamdari, E ; Haghshenas Fatmesari, D ; Darvishi, D ; Sadrnezhaad, S. K ; Sharif University of Technology
    Elsevier  2015
    Abstract
    In the present study, the thermodynamics and mechanisms of vanadium extraction by a mixture of bis-2-ethylhexyl phosphoric acid (D2EHPA) and tri-n butyl phosphate (TBP) from sulfate medium were investigated. It was found that the maximum extraction percent of vanadium occurs at pH 1.8 under ambient conditions; this phenomenon was ascribed to the predominant presence of cationic species of vanadium (VO2+) at this pH. Based on the Fourier Transform Infrared (FT-IR) spectrums, the POH bond of D2EHPA was found responsible for the extraction of VO2+ species through a cationic exchange mechanism. Employing the slope analysis method showed that the stoichiometric reaction... 

    Water adsorption in the organic phase for the D2EHPA-kerosene/water and aqueous Zn2+, Co2+, Ni2+ sulphate systems

    , Article Hydrometallurgy ; Volume 88, Issue 1-4 , 2007 , Pages 92-97 ; 0304386X (ISSN) Darvishi, D ; Haghshenas, D. F ; Etemadi, S ; Keshavarz Alamdari, E ; Sadrnezhaad, Kh ; Sharif University of Technology
    2007
    Abstract
    Water adsorption by bis-2-ethylhexyl phosphoric acid (D2EHPA) during the extraction of zinc, cobalt and nickel using a D2EHPA-kerosene/H2O mixture is investigated. Based on the experimental results, about 1 mol of water is adsorbed by 2 mol of D2EHPA (which exists in the form of a dimer), irrespective of the pH. Water adsorption decreases with presence of zinc, cobalt and nickel. The stoichiometric coefficients of D2EHPA in water adsorption reactions are determined with and without zinc, cobalt and nickel by applying the slope-analysis method. It is experimentally confirmed that 1.0, 1.8 and 1.2 mol of adsorbed water will be rejected from the organic phase when zinc, cobalt and nickel are... 

    Examining Steel Plate Shear Wall with Various Infill Plates Under Cyclic Loads

    , M.Sc. Thesis Sharif University of Technology Darvishi, Hadi (Author) ; Mofid, Massoud (Supervisor)
    Abstract
    In the present study, a number of Steel Plate Shear wall (SPSW) models with various infill plates such as perforated and slit infill panels are analyzed and the results are utilized to discuss about behavior of Steel Plate Shear walls with various infill plates. The ABAQUS finite element package is utilized for all Eigen value and incremental nonlinear pushover analyses. Cyclic loading is in compliance with the ATC 24 loading protocol (ATC 1992). To validate modeling, boundary conditions and loading procedures, the experimental results provided by Darren Vian et al. [102, 103] and In-Rak et al. [48, 49] was modeled and analyzed. Investigation of steel plate shear walls made of different... 

    Mathematical Modeling of Fixed bed Reactor for Oxidative Dehydrogenation (ODH) Process of Light Paraffins

    , M.Sc. Thesis Sharif University of Technology Darvishi, Ali (Author) ; khorashe, Farhad (Supervisor)
    Abstract
    An industrial scale reactor for light olefinsproduction was modelledusing the oxidative dehydrogenation (ODH) of light paraffinsin a multi-tubular reactor system involving 10000 small diameter tubes immersed in a shell with proper liquid-cooled flows. Here a theory-based pseudo-homogeneous 1-D model describing the operation of a fixed bed reactor for the ODHparaffinstoolefins over a Ni-Nb-O mixed oxide catalyst (for ethane) and over a V2O5/γ-Al2O3catalyst (for Propane),was employed. The paraffin and oxygen conversions, gas process and coolant temperatures, as well as other parameters affecting the reactor performance, including pressure, were examined. Furthermore, the applied model showed... 

    Analysis Of Financial Data With Statistical Methods

    , M.Sc. Thesis Sharif University of Technology Darvishi, Adel (Author) ; Moghaddasi, Reza (Supervisor)
    Abstract
    One of the important branches in machine learning is finding patterns and hidden features, which is useful for prediction and decision making in many cases. Finding patterns and features of financial data and particularly stock market data may play an important role in guidance, development and proper decision making related to such data sets. In this thesis, we focus on discovering and collecting appropriate methods in machine learning which can be helpful for gathering proper information from financial data and applying them on actual data  

    Cloud Computing Related to the Optimization of Compilation of Services from the Point of View of Cloud Computing Customers with A Multi-Objective Function in The Country's Office Equipment Manufacturing Industry

    , M.Sc. Thesis Sharif University of Technology Darvishi, Abdollah (Author) ; Houshmand, Mahmoud (Supervisor)
    Abstract
    Today, in order to keep up the competition in the market, companies need to use the latest technologies, methods, processes, applications, etc. to find the best services and products. For this, companies and organizations need more dynamism to make the best decisions that can accelerate business process changes. Cloud computing, which is one of the newest and most important business models, can contribute to their success by sharing information and production resources between organizations, as well as helping them compete globally with each other's capabilities. In this research, a multi-objective model is proposed to optimize customer decision-making in using cloud computing and the... 

    The Behavior of an Optomechanical System with Two Mechanical Modes in the Presence of Nonlinear Medium

    , M.Sc. Thesis Sharif University of Technology Darvishi, Morteza (Author) ; Bahrampour, Alireza (Supervisor)
    Abstract
    A cavity optomechanical system is created when the resonance frequency of an optical cavity is influenced by the position of a mechanical oscillator. To observe quantum effects and quantum applications of these systems, cooling of mechanical mode(s) participating in these interactions is very important. At first, the dissertation focus on the trend that people were trying to study radiation pressure theoretically and experimentally and then present classical and the quantum picture of radiation pressure. Next, the diverse geometries are based on the optomechanical interaction are described concisely. Fabry-Perot cavity with one degree of freedom has considered and then the Stokes and The... 

    Structural performance assessment of large unstiffened openings in steel plate shear walls

    , Article Engineering Structures ; Volume 247 , 2021 ; 01410296 (ISSN) Darvishi, H ; Mofid, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    The latest research studies on Steel Plate Shear Walls (SPSWs) suggest that the use of large-sized openings in infill plates calls for the use of heavy stiffeners or special measures for ensuring system stability. This study explores the effect of introduction of large unstiffened openings in SPSWs. A number of single story SPSWs with solid infill plates and their corresponding models with unstiffened openings are designed and analyzed numerically. In addition, this study provides a comparison of the experimental and numerical results obtained from the finite element models of SPSWs with openings. The results indicate the acceptable behavior of the specimens even at high levels of drift in... 

    Obtaining strain-rate dependent traction-separation law parameters of epoxy adhesive joints and predicting fracture for dissimilar bonding adherends

    , Article International Journal of Adhesion and Adhesives ; Volume 118 , 2022 ; 01437496 (ISSN) Darvishi, I ; Nourani, A ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    This study investigated the mode I fracture behavior of double cantilever beam (DCB) epoxy adhesive joints with similar adherends on the both sides (i.e., aluminum-aluminum or copper-copper) at different strain rates; i.e., quasi-static (∼10−3 s−1), low (∼7 s−1) and intermediate (∼14 s−1) rates. The fracture energy of the DCB joint in Al-adhesive-Al specimens decreased (i.e., by ∼62%, p = 0.0013) with an increase in the applied strain rate from quasi-static to low values, while it remained almost unchanged with further increase of stain rate to intermediate range (p > 0.05). For Cu-adhesive-Cu cases, however, the fracture energy was found to be almost insensitive to the applied strain rate... 

    Investigating the Fracture Behavior of Adhesive Joints at Different Strain Rates and under Drop

    , M.Sc. Thesis Sharif University of Technology Darvishi, Irana (Author) ; Nourani, Amir (Supervisor)
    Abstract
    Nowadays adhesives with the development of technology and the numerous benefits they have, are becoming a replacement for traditional joining methods in industries like electronics, automotive, aerospace, and naval. That’s why the need for studying the fracture behavior of adhesive joints becomes vital. So far, many engineers and designers are trying to investigate the behavior of adhesive joints in different conditions that these joints actually deal with. Also, finding solutions to predict the behavior of adhesive joints is the researchers’ other concern. The purpose of this research is to find the effect of factors that are less focused in the literature, on the fracture of adhesive... 

    Structural Performance Assessment of Large Unstiffened Openings in Steel Plate Shear Walls and Introduction of Plate-Frame Interaction in Steel Plate Shear Walls with Perforated Infill Plates

    , Ph.D. Dissertation Sharif University of Technology Darvishi, Hadi (Author) ; Mofid, Masood (Supervisor)
    Abstract
    One of the advantages of Steel Plate Shear Walls (SPSWs) is the possibility of using openings with varying sizes in the infill plates depending on a need basis. Openings are used for various reasons, such as the possibility of installing utilities and for architectural reasons. However, the latest research studies suggest that the use of large-sized openings in infill plates calls for the use of heavy stiffeners or special measures for ensuring system stability. The seismic behavior of two SPSWs with large unstiffened opening (one with a rectangular opening in the middle of the plate and the other with two oval openings on the sides of the infill plate) was studied experimentally and... 

    Investigating the Fracture Behavior of Adhesive Joints at Different Strain Rates and Under Drop

    , M.Sc. Thesis Sharif University of Technology Darvishi, Irana (Author) ; Nourani, Amir (Supervisor)
    Abstract
    Nowadays adhesives with the development of technology and the numerous benefits they have, are becoming a replacement for traditional joining methods in industries like electronics, automotive, aerospace, and naval. That’s why the need for studying the fracture behavior of adhesive joints becomes vital. So far, many engineers and designers are trying to investigate the behavior of adhesive joints in different conditions that these joints actually deal with. Also, finding solutions to predict the behavior of adhesive joints is the researchers’ other concern. The purpose of this research is to find the effect of factors that are less focused in the literature, on the fracture of adhesive... 

    MHC-Peptide Binding Prediction Using a Deep Learning Method with Efficient GPU Implementation Approach

    , M.Sc. Thesis Sharif University of Technology Darvishi, Saeed (Author) ; Koohi, Somayyeh (Supervisor)
    Abstract
    The Major Histocompatibility Complex (MHC) binds to the derived peptides from pathogens to present them to killer T cells on the cell surface. Developing computational methods for accurate, fast, and explainable peptide-MHC binding prediction can facilitate immunotherapies and vaccine development. Various deep learning-based methods rely on feature extraction from the peptide and MHC sequences separately and ignore their valuable binding information. This paper develops a capsule neural network-based method to efficiently capture and model the peptide-MHC complex features to predict the peptide- MHC class I binding. Various evaluations over multiple datasets using popular performance metrics... 

    A Study on the Relationship Between Muscle, Kinematics, and Kinetic Synergies During Human Gait

    , M.Sc. Thesis Sharif University of Technology Darvishi, Mahziyar (Author) ; Farahmand, Farzam (Supervisor)
    Abstract
    Human body movements are achieved by activating a number of muscles. It has been shown that the central nervous system (CNS) plays the main role in controlling rhythmic activities (including walking, chewing, etc.). However, the way the central nervous system works in controlling different parts of the body has always been discussed due to the excess degrees of freedom to perform certain tasks. Controlling a group of muscles (under the name of muscle synergy analysis) instead of each one of them has been one of the most attractive and efficient recent ideas to better understand the CNS function. Also, a similar concept can be expressed for kinematic synergies (by the degrees of freedom of... 

    Synergistic effect of Cyanex 272 and Cyanex 302 on separation of cobalt and nickel by D2EHPA

    , Article Hydrometallurgy ; Volume 77, Issue 3-4 , 2005 , Pages 227-238 ; 0304386X (ISSN) Darvishi, D ; Haghshenas, D. F ; Keshavarz Alamdari, E ; Sadrnezhaad, S. K ; Halali, M ; Sharif University of Technology
    2005
    Abstract
    Synergistic effects of Cyanex 272 mixed with D2EHPA and Cyanex 302 mixed with D2EHPA were investigated for the separation of cobalt and nickel from a dilute sulfate media with the aim of reducing the reagent cost. Selective extraction of cobalt over nickel improved with respect to D2EHPA, but worsened with respect to Cyanex 272. By the application of the slope analysis method, the stoichiometric coefficient of the extractant was found to be four for cobalt and five for nickel, in a mixture of D2EHPA with Cyanex 302. However, it was four for both cobalt and nickel in a mixture of D2EHPA with Cyanex 272. Fourier Transform Infrared Spectroscopy (FT-IR) was utilized to examine the... 

    Effects of rock permeability on capillary imbibition oil recovery from carbonate cores

    , Article Scientia Iranica ; Volume 17, Issue 2 C , JULY-DECEMBER , 2010 , Pages 185-190 ; 10263098 (ISSN) Darvishi, H ; Goodarznia, I ; Esmaeilzadeh, F ; Sharif University of Technology
    2010
    Abstract
    In order to investigate the feasibility and effects of core permeability on capillary imbibition recoverable oil from carbonate cores, some laboratory tests were carried out at the EOR research laboratories of Sharif University, Iran. Outcrop rocks with different permeabilities were taken away from a recognized outcrop and used in these experiments. Special core analysis tests were run on two core samples to find out relative permeability and end point saturations. Wellhead separator oil and gas samples were collected and recombined to a reservoir gas - oil ratio. A core flooding system with a capability of free and forced imbibition testing was designed and installed. A number of free and... 

    Modeling-based optimization of a fixed-bed industrial reactor for oxidative dehydrogenation of propane

    , Article Chinese Journal of Chemical Engineering ; Volume 24, Issue 5 , 2016 , Pages 612-622 ; 10049541 (ISSN) Darvishi, A ; Davand, R ; Khorasheh, F ; Fattahi, M ; Sharif University of Technology
    Chemical Industry Press  2016
    Abstract
    An industrial scale propylene production via oxidative dehydrogenation of propane (ODHP) in multi-tubular reactors was modeled. Multi-tubular fixed-bed reactor used for ODHP process, employing 10000 of small diameter tubes immersed in a shell through a proper coolant flows. Herein, a theory-based pseudo-homogeneous model to describe the operation of a fixed bed reactor for the ODHP to correspondence olefin over V2O5/γ-Al2O3 catalyst was presented. Steady state one dimensional model has been developed to identify the operation parameters and to describe the propane and oxygen conversions, gas process and coolant temperatures, as well as other parameters affecting the reactor performance such... 

    Condensate blockage study in gas condensate reservoir

    , Article Journal of Natural Gas Science and Engineering ; Volume 33 , 2016 , Pages 634-643 ; 18755100 (ISSN) Rahimzadeh, A ; Bazargan, M ; Darvishi, R ; Mohammadi, A. H ; Sharif University of Technology
    Elsevier  2016
    Abstract
    The effect of condensate blockage on the pressure drop near the well bore has been studied. Two types of single well simulations have been conducted and pressure drop due to condensate blockage has been quantified based on variation of gas relative permeabilities in near well bore area. The relationship of condensate banking pressure drop, gas rate and reservoir quality has been presented. It is shown that for a poor reservoir quality, condensate blockage can increase the pressure drop up to 200% of the pressure drop in the tubing