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    Structural and transport properties of polydimethylsiloxane based polyurethane/silica particles mixed matrix membranes for gas separation

    , Article Korean Journal of Chemical Engineering ; Volume 31, Issue 5 , 2014 , Pages 841-848 ; ISSN: 02561115 Semsarzadeh, M. A ; Ghalei, B ; Fardi, M ; Esmaeeli, M ; Vakili, E ; Sharif University of Technology
    Abstract
    Mixed matrix membranes of synthesized polyurethane (PU) based on toluene diisocyanate (TDI), polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) with polyvinyl alcohol based polar silica particles were prepared by solution casting technique. The homogeneity and thermal properties of the prepared PDMS-PU/silica membranes were characterized using scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The SEM micrographs confirmed the distribution of silica particles in the polymer matrix without agglomerations. Gas permeation properties of membranes with different silica contents were studied for pure CO2, CH4, O2, He... 

    Simulation of body force field effects on airfoil separation control and optimization of plasma actuator

    , Article Journal of Physics D: Applied Physics ; Volume 41, Issue 17 , 2008 ; 00223727 (ISSN) Abdoli, A ; Mirzaee, I ; Anvari, A ; Purmahmod, N ; Sharif University of Technology
    2008
    Abstract
    Among all active flow control methods, EHD, MHD and EMHD are the only methods which operate on the basis of body force induction on flow field. The EHD plasma actuator is the proper method which has been used in various flow control applications recently. In this paper, the effects of different body force fields on different domains have been studied for separation control on NACA 0021 and the results have been discussed. The airflow velocity has been assumed to be 35 m s-1 at a post-stall angle of attack of 23°. Three different domains have been used around the airfoil to investigate body forces with different strengths and directions and those which give the best result in separation... 

    Supersonic Separation

    , M.Sc. Thesis Sharif University of Technology Daryaie, Mohammad Reza (Author) ; Moosavi, Ali (Supervisor) ; Nouri Borujerdi, Ali (Supervisor)
    Abstract
    Supersonic separators with neither rotating parts nor chemical process, physically separate particles in a multi-phase flow. In comparison with general separation techniques, which are utilized in industries, specifically this equipment is cheaper, smaller and lighter. Condensation and separation at supersonic velocity is the key to achieve a significant reduction in both capital and operating costs. In this study, a two dimensional de Laval nozzle and few three-dimensional supersonic separator have been modeled. The 3D models modified in shape and dimensions. Impellers were created to form swirl flow. The models were simulated by the use of CFD software ANSYS FLUENT. Diverse inlet pressures... 

    New constructions of SSPDs and their applications

    , Article Computational Geometry: Theory and Applications ; Volume 45, Issue 5-6 , 2012 , Pages 200-214 ; 09257721 (ISSN) Abam, M. A ; Har Peled, S ; Sharif University of Technology
    2012
    Abstract
    We present a new optimal construction of a semi-separated pair decomposition (i.e., SSPD) for a set of n points in Rd. In the new construction each point participates in a few pairs, and it extends easily to spaces with low doubling dimension. This is the first optimal construction with these properties. As an application of the new construction, for a fixed t>1, we present a new construction of a t-spanner with O(n) edges and maximum degree O( log2n) that has a separator of size O(n1 -1/d)  

    LPG mass separation by vortex tube cascade and its economics

    , Article Applied Thermal Engineering ; Volume 148 , 2019 , Pages 1139-1147 ; 13594311 (ISSN) Majidi, D ; Alighardashi, H ; Farhadi, F ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    In the present experimental study, the effect of operating parameters such as inlet and outlet pressure as well as inlet temperature on the mass separation capability of vortex tubes (VTs) for a gas mixture is investigated. Specifically, concentrating heavier components of a gas mixture in the hot outlet stream is considered. Proposing a semi-empirical index from the experimental study, the simulation of different arrangements of VTs, and the effect of recycling a portion of the hot outlet stream on its mass separation performance are investigated. Moreover, the proposed separation method by VTs is economically compared with commonly used methods by distillation columns and two-phase... 

    Experimental investigation and mathematical modeling of oil/water emulsion separation effectiveness containing alkali-surfactant-polymer

    , Article Journal of Dispersion Science and Technology ; Volume 42, Issue 9 , 2021 , Pages 1286-1298 ; 01932691 (ISSN) Aleem, W ; Mellon, N ; Khan, J. A ; Al-Kayiem, H. H ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Abstract
    Alkalis, surfactants and/or polymers are usually injected in the injector wells so that the injection fluids can sweep through the reservoir and mobilize/recover more oil. However, the formation of stable emulsion due to the residual chemicals in the recovered crude oil poses problems in the primary separation process. This study focuses on the effect of Alkali-Surfactant-Polymer injection on creaming and coalescence of crude oil and water emulsion produced in the primary gravity separator. In addition, a model is developed in this work to predict the separation effectiveness of oil and water emulsion containing ASP. In this work, the effect of ASP on the stability and the separation of... 

    Experimental investigation and mathematical modeling of oil/water emulsion separation effectiveness containing alkali-surfactant-polymer

    , Article Journal of Dispersion Science and Technology ; Volume 42, Issue 9 , 2021 , Pages 1286-1298 ; 01932691 (ISSN) Aleem, W ; Mellon, N ; Khan, J. A ; Al-Kayiem, H. H ; Sharif University of Technology
    Bellwether Publishing, Ltd  2021
    Abstract
    Alkalis, surfactants and/or polymers are usually injected in the injector wells so that the injection fluids can sweep through the reservoir and mobilize/recover more oil. However, the formation of stable emulsion due to the residual chemicals in the recovered crude oil poses problems in the primary separation process. This study focuses on the effect of Alkali-Surfactant-Polymer injection on creaming and coalescence of crude oil and water emulsion produced in the primary gravity separator. In addition, a model is developed in this work to predict the separation effectiveness of oil and water emulsion containing ASP. In this work, the effect of ASP on the stability and the separation of... 

    A new method for separation of speech signals in convolutive mixtures

    , Article 13th European Signal Processing Conference, EUSIPCO 2005, Antalya, 4 September 2005 through 8 September 2005 ; 2005 , Pages 2210-2213 ; 1604238216 (ISBN); 9781604238211 (ISBN) Ferdosizadeh, M ; Babaie Zadeh, M ; Marvasti, F. A ; Sharif University of Technology
    2005
    Abstract
    In this paper, the performance of the gradient method based on Score Function Difference (SFD) in the separation of i.i.d. and periodic signals will be investigated. We will see that this algorithm will separate periodic signals better than i.i.d. ones. By using this experimental result and the fact that voiced frames of speech signals are approximately periodic, a modified algorithm named VDGaradient has been proposed for separation of speech signals in synthetic convolutive mixtures. In this method, voiced frames of speech signal will be used as the input to the gradient method, then the resulting separating system will be applied to separate sources completely  

    Calculation of the density and activity of water in ATPS systems for separation of biomolecules

    , Article Journal of Solution Chemistry ; Volume 42, Issue 7 , 2013 , Pages 1423-1437 ; 00959782 (ISSN) Valavi, M ; Shirazian, S ; Pour, A. F ; Ziary, M ; Sharif University of Technology
    2013
    Abstract
    In this study, the perturbed hard sphere chain equation of state is utilized to calculate the activity of water in binary and ternary solutions of polyethylene glycol (PEG), salt and water. The liquid density of the binary and ternary solutions is also predicted. To estimate the water activity in PEG-water binary systems, a linear correlation is obtained for the binary interaction parameter between water and PEG. Then, using this correlation and without introducing any additional binary parameters, the water activities are predicted in ternary solutions of water, salt and PEG with different molecular weights (MW). Our results show that the mean absolute average relative deviation (AARD %) of... 

    Continuous size-based focusing and bifurcating microparticle streams using a negative dielectrophoretic system

    , Article Microfluidics and Nanofluidics ; Volume 14, Issue 1-2 , 2013 , Pages 265-276 ; 16134982 (ISSN) Hemmatifar, A ; Saidi, M. S ; Sadeghi, A ; Sani, M
    2013
    Abstract
    Dielectrophoresis (DEP) is an electrokinetic phenomenon which is used for manipulating micro- and nanoparticles in micron-sized devices with high sensitivity. In recent years, electrode-based DEP by patterning narrow oblique electrodes in microchannels has been used for particle manipulation. In this theoretic study, a microchannel with triangular electrodes is presented and a detailed comparison with oblique electrodes is made. For each shape, the behavior of particles is compared for three different configurations of applied voltages. Electric field, resultant DEP force, and particle trajectories for configurations are computed by means of Rayan native code. The separation efficiency of... 

    Three easy ways for separating nonlinear mixtures?

    , Article Signal Processing ; Volume 84, Issue 2 , 2004 , Pages 217-229 ; 01651684 (ISSN) Jutten, C ; Babaie Zadeh, M ; Hosseini, S ; Sharif University of Technology
    2004
    Abstract
    In this paper, we consider the nonlinear Blind Source Separation BSS and independent component analysis (ICA) problems, and especially uniqueness issues, presenting some new results. A fundamental difficulty in the nonlinear BSS problem and even more so in the nonlinear ICA problem is that they are nonunique without a suitable regularization. In this paper, we mainly discuss three different ways for regularizing the solutions, that have been recently explored. © 2003 Elsevier B.V. All rights reserved  

    A geometric approach for separating several speech signals

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Volume 3195 , 2004 , Pages 798-806 ; 03029743 (ISSN); 3540230564 (ISBN); 9783540230564 (ISBN) Babaie Zadeh, M ; Mansour, A ; Jutten, C ; Marvasti, F ; Sharif University of Technology
    Springer Verlag  2004
    Abstract
    In this paper a new geometrical approach for separating speech signals is presented. This approach can be directly applied to separate more than two speech signals. It is based on clustering the observation points, and then fitting a line (hyper-plane) onto each cluster. The algorithm quality is shown to be improved by using DCT coefficients of speech signals, as opposed to using speech samples. © Springer-Verlag 2004  

    Experimental modeling of vortex tube refrigerator

    , Article Applied Thermal Engineering ; Volume 23, Issue 15 , 2003 , Pages 1971-1980 ; 13594311 (ISSN) Saidi, M. H ; Valipour, M. S ; Sharif University of Technology
    2003
    Abstract
    An experimental investigation has been performed to realize thorough behavior of a vortex tube system. In this work attention has been focussed on the classification of the parameters affecting vortex tube operation. The effective parameters are divided into two different types, namely geometrical and thermo-physical ones. A reliable test rig has been designed and constructed to investigate the effect of geometrical parameters i.e. diameter and length of main tube, diameter of outlet orifice, shape of entrance nozzle. Thermo-physical parameters which have been designated and studied are inlet gas pressure, type of gas, cold gas mass ratio and moisture of inlet gas. The effects of these... 

    Improving productivity through increased capacity

    , Article World Cement ; Volume 34, Issue 7 , 2003 , Pages 99-105 ; 02636050 (ISSN) Safaieh, M. R ; Kakuei, A ; Sharif University of Technology
    2003
    Abstract
    The upgradation of the Kerman cement plant in Iran was discussed. It produces type 2,5 and pozzolanic cements which constitute almost 4.2% of the cement used in Iran. A short description of the process used, and some observations and recommendations about the plant were also provided  

    On the gap between separating words and separating their reversals

    , Article Theoretical Computer Science ; 2017 ; 03043975 (ISSN) Ebrahimnejad, F ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    A deterministic finite automaton (DFA) separates two strings w and x if it accepts w and rejects x. The minimum number of states required for a DFA to separate w and x is denoted by sep(w,x). The present paper shows that the difference |sep(w,x)-sep(wR,xR)| is unbounded for a binary alphabet; here wR stands for the mirror image of w. This solves an open problem stated in Demaine et al. (2011) © 2017 Elsevier B.V  

    Two multimodal approaches for single microphone source separation

    , Article European Signal Processing Conference, 28 August 2016 through 2 September 2016 ; Volume 2016-November , 2016 , Pages 110-114 ; 22195491 (ISSN ; 9780992862657 (ISBN) Sedighin, F ; Babaie Zadeh, M ; Rivet, B ; Jutten, C ; Sharif University of Technology
    European Signal Processing Conference, EUSIPCO  2016
    Abstract
    In this paper, the problem of single microphone source separation via Nonnegative Matrix Factorization (NMF) by exploiting video information is addressed. Respective audio and video modalities coming from a single human speech usually have similar time changes. It means that changes in one of them usually corresponds to changes in the other one. So it is expected that activation coefficient matrices of their NMF decomposition are similar. Based on this similarity, in this paper the activation coefficient matrix of the video modality is used as an initialization for audio source separation via NMF. In addition, the mentioned similarity is used for post-processing and for clustering the rows... 

    Effect of the wet outlet geometry on the shockwave position in supersonic separators

    , Article Chemical Engineering and Technology ; Volume 43, Issue 1 , January , 2020 , Pages 126-136 Majidi, D ; Farhadi, F ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    Abstract
    Supersonic separators (3Ss) are applied in gas separation processes. Two-dimensional simulation is employed to investigate the effect of operational and thermophysical parameters on the shockwave position. In addition, the impact of the cyclonic part and wet outlet geometry is evaluated by proposing four cases. Increasing the length of the cyclonic part exerts positive and negative influences on the performance of the 3S and the pressure recovery coefficient, respectively. The optimum length is determined between 10 and 15 cm. To demonstrate negative effects of wasted air from the wet outlet, its flow has been increased from 3.6 to 8.1 % of the inlet flow. Improved performance of the 3S is... 

    Study on Momentary and Overall Separation Factors in Lithium Isotopes Separation by Batch Electrolysis

    , M.Sc. Thesis Sharif University of Technology Azad, Mohsen (Author) ; Otukesh, Mohammad (Supervisor) ; Ahmadi, Javad (Supervisor) ; Kowsari, Mohammad Reza ($item.subfieldsMap.e)
    Abstract
    Lithium has two stable isotopes, 6Li and 7Li. Abundance of these isotopes are 7.53% and 92.43% respectively. Each isotope has an important role in nuclear industry. For example, 6Li compounds is used in production of tritium in nuclear fusion reactors coated with DT fuel and as fuel in nuclear fusion reactors that operate with laser inertial confinement method applied. 7LiOH is used to adjust the pH of the fluid coolant in light water reactors and also in Breeding Reactors. Lithium isotope separation in different ways so far been brought into operation. The other aspect to this work, it can be both continuous and batch for action. Lithium isotopes for the first time by electrolysis using... 

    Application of genetic algorithm for optimization of separator pressures in multistage production units

    , Article Chemical Engineering Communications ; Vol. 201, issue. 7 , 2014 , p. 926-938 Ghaedi, M ; Ebrahimi, A. N ; Pishvaie, M. R ; Sharif University of Technology
    Abstract
    In this article, a genetic algorithm is used to optimize the separator pressures in a multistage crude oil and multistage gas condensate production unit with four and three separators respectively. This leads to the generation of more accurate results for the quality and quantity of oil remaining in the stock tank for both crude oil and gas condensate production units. Genetic-based optimized pressures for crude oil separators resulted in 1.8% and 2% enhancement in oil remaining in the stock tank for summer and winter respectively. API gravity of the stock tank oil was improved 2.4% in summer and 2.2% in winter. For the gas condensate production unit, optimized pressures can enhance by 8.6%... 

    System and method for analysis of involving factors in the demisting cyclone efficiency

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), San Diego, CA ; Volume 15 , November , 2013 ; 9780791856444 (ISBN) Najafabadi, M. M ; Ehteram, M. A ; Ahmadian, M. T ; Barari, A ; ASME ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2013
    Abstract
    In this study a system for real-time analysis of some involving factors in the efficiency of gas-liquid separators is developed based on the weighing method. An ultrasonic atomizer generates water drops in a size range of 1-10 μm with the same frequency during the test. A cyclone separator is selected and effect of the developing flow rate and shape of the mini-riser as a part of connecting assembly to the cyclone separator is investigated. Further an efficient electrostatic precipitator (ESP) with outcome of single-phase airflow is employed in the downstream of the cyclone to separate remaining droplets and produce the same pressure loss during the test. Circular, triangular, rectangular...