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    Inhibiting asphaltene precipitation from Iranian crude oil using various dispersants: Experimental investigation through viscometry and thermodynamic modelling

    , Article Fluid Phase Equilibria ; Volume 442 , 2017 , Pages 104-118 ; 03783812 (ISSN) Saeedi Dehaghani, A. H ; Badizad, M. H ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    Asphaltene precipitation is a major assurance problem posing significant technical and economic loss on petroleum industry. To tackle this issue, various treatments have been proposed and applied by industry. Amongst, inhibiting or retarding the asphaltene precipitation has been understood as the most efficient approach. In this regard, blending crude oil with chemical additives could appreciably heighten its stability. Surfactants, owing to amphiphilic nature, could keep asphaltene dissolved in crude oil by precluding self-tendency of those particles to making agglomerates. Despite importance of this subject, there is still lack of sufficient experimental data to evaluate effectiveness of... 

    Effect of magnetic field treatment on interfacial tension of CTAB nano-emulsion: developing a novel agent for enhanced oil recovery

    , Article Journal of Molecular Liquids ; Volume 261 , July , 2018 , Pages 107-114 ; 01677322 (ISSN) Saeedi Dehaghani, A. H ; Badizad, M. H ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    Nanoemulsion is a novel type of emulsified solutions holding great promises for utilizing in industrial applications. Although microemulsions have been the subject of numerous studies in past decades, however, nanoemulsions are quite virgin and merit detailed investigation to scrutinize their characteristics specific to reservoir engineering, in particular, Enhanced Oil Recovery (EOR). To this end, the present study is an attempt to evaluate the effectiveness of a specific nanoemulsion for oil displacement through porous media. In this regard, flooding experiments were designed and Hexa decyl trimethylammonium bromide (CTAB), which is a cationic surfactant, was used as the emulsifying agent.... 

    Impact of ionic composition on modulating wetting preference of calcite surface: Implication for chemically tuned water flooding

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 568 , 2019 , Pages 470-480 ; 09277757 (ISSN) Saeedi Dehaghani, A. H ; Badizad, M. H ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Despite previous researches on ion-engineered waterflooding (IEWF), its underlying mechanisms are not fully understood, particularly in presence of additives, like surfactants. This paper concerned with the contribution of Ca 2+ , Mg 2+ , SO 4 2- and Na + into altering wettability of oil-wet carbonate minerals towards water preferred state. As a mechanistic study, an experiment workflow was conducted to probe the impact of ions' concentrations in SW, either with or without sodium dodecylbenzene sulfonate (SDBS) which is an anionic surfactant. At first, contact angle (CA) measurement was carried out to evaluate the degree of wettability reversal upon treating the oil-aged calcite slabs with... 

    Extending application of Dehaghani Association Equation of State for Modeling Phase Behavior of Water-Alcohol Systems

    , Article Fluid Phase Equilibria ; Volume 482 , 2019 , Pages 126-133 ; 03783812 (ISSN) Saeedi Dehaghani, A. H ; Badizad, M. H ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    This paper concerns extending applicability of Dehaghani association equation of state (in short DA-EOS) to model non-ideality in phase behavior caused by hydrogen bonding. Advantageously, this equation only needs two and one parameters to treat self- and cross association, respectively, which were determined for methanol/water and ethanol/water mixture in this study. In this respect, DA was coupled with PR and SRK EOS to account for physical interaction between molecules. Notably, DA-PR persistently provides more accurate prediction than DA-SRK for both aqueous methanol and ethanol solutions  

    Developing a novel colloidal model for predicting asphaltene precipitation from crude oil by alkane dilution

    , Article Journal of Molecular Liquids ; Volume 318 , 2020 Shadman, M. M ; Badizad, M. H ; Dehghanizadeh, M ; Saeedi Dehaghani, A. H ; Sharif University of Technology
    Elsevier B.V  2020
    Abstract
    This research aims to propose a thermodynamic model for predicting asphaltene precipitation upon diluting a crude oil with a paraffinic solvent. To this end, a thorough mathematical formulation was carried out to derive a novel micellization model based on the associative properties of asphaltenic compounds. It was assumed that asphaltenes exist in the oil both as monomeric molecules and aggregated cores; with stabilization latter by attachment of resin on its periphery. The aggregation equilibrium was established by taking into account asphaltene's lyophobic tendency, heat of resin adsorption, and interfacial tension between micelle and oil media which is the main driving factor... 

    Simulation study of the Gachsaran asphaltene behavior within the interface of oil/water emulsion: a case study

    , Article Colloids and Interface Science Communications ; Volume 33 , 2019 ; 22150382 (ISSN) Saeedi Dehaghani, A. H ; Soodbakhsh Taleghani, M ; Badizad, M. H ; Daneshfar, R ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Molecular dynamics (MD) simulation was utilized to study the role of asphaltene extracted from Gachsaran (an Iranian oilfield) at the synthetic oil-water interface. In agreement with experimental data, IFTs predicted by MD simulation for heptol/brine system showed a minima at around 50 vol.% n-heptane, reflecting the highest contribution of asphaltene into the interface. At greater n-heptane fractions, IFT was increased steadily. Simulation results suggest the asphaltene propensity for remaining in the bulk heptol phase rather related to the fraction of toluene in the mixture. Heptol ingredients, i.e., toluene and heptane, act differently with respect to asphaltene, where former tends to... 

    Modeling of asphaltene precipitation in calculation of minimum miscibility pressure

    , Article Industrial and Engineering Chemistry Research ; Volume 56, Issue 25 , 2017 , Pages 7375-7383 ; 08885885 (ISSN) Kariman Moghaddam, A ; Saeedi Dehaghani, A. H ; Sharif University of Technology
    American Chemical Society  2017
    Abstract
    An algorithm has been developed to investigate the effect of asphaltene precipitation on calculation of minimum miscibility pressure (MMP), which is one of the key design parameters of any gas injection projects. In fact, this algorithm is the extension of procedure suggested by Jaubert et al. for prediction of MMP whatever the displacement mechanism. The vapor-liquid equilibrium calculation and then liquid-liquid equilibrium calculation are required to be taken account to estimate the amount of asphaltene precipitation. The association equation of state (AEOS) has been applied to determine the phase behavior of asphaltene. The algorithm has been used for the MMP prediction of Weyburn... 

    New sequences of capacity achieving LDPC code ensembles over the binary erasure channel

    , Article IEEE Transactions on Information Theory ; Volume 56, Issue 12 , 2010 , Pages 6332-6346 ; 00189448 (ISSN) Saeedi, H ; Banihashemi, A. H ; Sharif University of Technology
    2010
    Abstract
    In this paper, new sequences (λn,ρn) of capacity achieving low-density parity-check (LDPC) code ensembles over the binary erasure channel (BEC) is introduced. These sequences include the existing sequences by Shokrollahi as a special case. For a fixed code rate R, in the set of proposed sequences, Shokrollahi's sequences are superior to the rest of the set in that for any given value of n, their threshold is closer to the capacity upper bound 1 - R. For any given δ, 0 < δ < 1 - R, however, there are infinitely many sequences in the set that are superior to Shokrollahi's sequences in that for each of them, there exists an integer number n0, such that for any n > n0, the sequence (λn, ρn)... 

    Biodesulfurization of dibenzothiophene by a newly isolated Rhodococcus erythropolis strain

    , Article Bioresource Technology ; Volume 101, Issue 3 , 2010 , Pages 1102-1105 ; 09608524 (ISSN) Davoodi Dehaghani, F ; Vosoughi, M ; Ziaee, A. A ; Sharif University of Technology
    2010
    Abstract
    A new dibenzothiophene (DBT) desulfurizing bacterium was isolated from oil-contaminated soils in Iran. HPLC analysis and PCR-based detection of the presence of the DBT desulfurization genes (dszA, dszB and dszC) indicate that this strain converts DBT to 2-hydroxybiphenyl (2-HBP) via the 4S pathway. The strain, identified as Rhodococcus erythropolis SHT87, can utilize DBT, dibenzothiophene sulfone, thiophene, 2-methylthiophene and dimethylsulfoxide as a sole sulfur source for growth at 30 °C. The maximum specific desulfurization activity of strain SHT87 resting cells in aqueous and biphasic organic-aqueous systems at 30 °C was determined to be 0.36 and 0.47 μmol 2-HBP min-1 (g dry cell)-1,... 

    Effects of auxetic shoe on lumbar spine kinematics and kinetics during gait and drop vertical jump by a combined in vivo and modeling investigation

    , Article Scientific Reports ; Volume 12, Issue 1 , 2022 ; 20452322 (ISSN) Dehaghani, M. R ; Nourani, A ; Arjmand, N ; Sharif University of Technology
    Nature Research  2022
    Abstract
    The present study examined the effects of auxetic shoes on the biomechanics of the spine, as compared to barefoot and conventional shoe conditions, during gait and drop vertical jump (DVJ) activities using a combined in vivo and musculoskeletal modeling approach. Motion and force-plate data as well as electromyographic (EMG) activities of select trunk muscles of 11 individuals were collected during foregoing activities. In DVJ activity, two main phases of first landing (FL) and second landing (SL) were studied. In the FL phase of DVJ noticeable alternations were observed when auxetic shoes were used. That is, compared to the conventional footwear condition, smaller EMG activities in extensor... 

    Belief propagation-based multiuser receivers in optical code-division multiple access systems

    , Article IET Communications ; Volume 7, Issue 18 , 2013 , Pages 2102-2112 ; ISSN: 17518628 Sedaghat, M. A ; Nezamalhosseini, A ; Saeedi, H ; Marvasti, F ; Sharif University of Technology
    2013
    Abstract
    In this study, the authors investigate the performance of optical code-division multiple access (OCDMA) systems with belief propagation (BP)-based receivers. They propose three receivers for the optical fibre channel that provide a trade-off between detecting complexity and system performance. The first proposed receiver achieves a performance very close to the so-called known interference lower bound. The second receiver exhibits a considerably less complexity at the expense of a slight degradation in performance. They show that the third BP-based receiver, which is a simplified version of the second receiver, is surprisingly the same as the so-called multistage detector in OCDMA systems.... 

    A 1-V 400MS/s 14bit self-calibrated CMOS DAC with enhanced dynamic linearity

    , Article 2004 IEEE International Symposium on Circuits and Systems - Proceedings, Vancouver, BC, 23 May 2004 through 26 May 2004 ; Volume 1 , 2004 , Pages I349-I352 ; 02714310 (ISSN) Saeedi, S ; Mehrmanesh, S ; Atarodi, M ; Aslanzadeh, H. A ; Sharif University of Technology
    2004
    Abstract
    A 1-V CMOS current steering digital to analog converter with enhanced static and dynamic linearity is presented. The 14-bit static linearity is achieved by a novel background analog self calibration technique which is suitable for low voltage applications and does not require error measurement and correction circuits. To improve dynamic linearity at high frequencies, a new low power track/attenuate output stage is used at the DAC output. Integral and differential nonlinearities of the proposed DAC corresponding, to 14-bit specification are less than 0.35LSB and 0.25LSB, respectively. The DAC is functional up to 400MS/S with SFDR better than 71dB in the Nyquist band. The circuit has been... 

    A new full CMOS 2.5-V two-stage line driver with variable gain for ADSL applications

    , Article 2004 IEEE International Symposium on Circuits and Systems - Proceedings, Vancouver, BC, 23 May 2004 through 26 May 2004 ; Volume 4 , 2004 , Pages IV-405-IV-408 ; 02714310 (ISSN) Mehrmanesh, S ; Atarodi, M ; Aslanzadeh, H. A ; Saeedi, S ; Safarian, A. Q ; Sharif University of Technology
    2004
    Abstract
    In this paper a new low-voltage two-stage class-AB line driver for ADSL applications is presented. The new proposed line-driver consists of only two stages with a new method to control the quiescent current of the output stage. The low-voltage full-CMOS high-linear line driver shows -77 dB THD for a load as low as 20 ohms. The line driver has variable gain, attenuating the input signal from 0dB to -14dB with 2dB steps. The peak to peak differential output swing is 4.2-V from a 2.5-V Supply voltage in a 0.25um standard CMOS technology  

    A new insight to the assessment of asphaltene characterization by using fortier transformed infrared spectroscopy

    , Article Journal of Petroleum Science and Engineering ; Volume 205 , 2021 ; 09204105 (ISSN) Taherian, Z ; Saeedi Dehaghani, A ; Ayatollahi, S ; Kharrat, R ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    This research aims to present asphaltene fraction of oil by FTIR spectrum technique. For this purpose, three different oil samples with various SARA contents and almost identical API degrees were utilized in this research. Two asphaltenic oil samples were referred to as ‘A’ and ‘B’, and the aliphatic oil sample was named as ‘C’. First of all, the asphaltene fraction was extracted through the IP-143 test. The possible chemical bonds and functional groups were identified through NMR tests. Then, the FTIR spectrums of the oil samples and the extracted corresponding asphaltene fractions were taken. The interpretations were used to find the functional groups in the FTIR of the oil samples that... 

    The mechanistic investigation on the effect of the crude oil /brine interaction on the interface properties: A study on asphaltene structure

    , Article Journal of Molecular Liquids ; Volume 360 , 2022 ; 01677322 (ISSN) Taherian, Z ; Saeedi Dehaghani, A ; Ayatollahi, S ; Kharrat, R ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    Despite many attempts to study the interaction of fluids in low-salinity flooding, they do not examine the principles of interphasic transition phenomena. This study aims to provide a new understanding of liquid–liquid interactions during the low-salinity water interaction through a series of experiments on the oil, emulsion, and aqueous phase. Three samples of crude oils with different asphaltene concentrations and structures with known physical properties are in contact with different solutions. The brine pH, conductivity, and crude oil viscosity experiments before and after contacting the oil with brine showed that the heteroatom concentration and compaction of crude oil asphaltene... 

    Evaluation of water desalination performances of functionalized nanoporous graphene membranes by molecular dynamics simulation

    , Article Computational Materials Science ; Volume 228 , 2023 ; 09270256 (ISSN) Zarghami Dehaghani, M ; Mashhadzadeh, A. H ; Vafa, N ; Firoozabadi, B ; Nouranian, S ; Golman, B ; Spitas, C ; Sharif University of Technology
    Elsevier B.V  2023
    Abstract
    Nanoporous graphene membrane (NPGM) is a promising candidate for water desalination due to its unique features, such as chemical stability, high resistance to chlorine and fouling, excellent mechanical strength, and tunable permeability. In this work, the water desalination performances of small- and large-pore, pristine and functionalized NPGMs, with the latter containing amide, sulfonic acid, thiourea, and carbamate functional groups, were evaluated by molecular dynamics (MD) simulation. Our results indicate that pore functionalization leads to a decrease in water flow rate through the membrane. Among functionalized NPGMs, large-pore, amide-functionalized NPGM exhibited the highest water... 

    Capacity achieving linear codes with random binary sparse generating matrices over the binary symmetric channel

    , Article IEEE International Symposium on Information Theory - Proceedings ; 2012 , Pages 621-625 ; 9781467325790 (ISBN) Kakhaki, A. M ; Abadi, H. K ; Pad, P ; Saeedi, H ; Marvasti, F ; Alishahi, K ; Sharif University of Technology
    IEEE  2012
    Abstract
    In this paper, we prove the existence of capacity achieving linear codes with random binary sparse generating matrices over the Binary Symmetric Channel (BSC). The results on the existence of capacity achieving linear codes in the literature are limited to the random binary codes with equal probability generating matrix elements and sparse parity-check matrices. Moreover, the codes with sparse generating matrices reported in the literature are not proved to be capacity achieving for channels other than Binary Erasure Channel. As opposed to the existing results in the literature, which are based on optimal maximum a posteriori decoders, the proposed approach is based on a different decoder... 

    Fluid-structure interaction simulation of blood flow and cerebral aneurysm: effect of partly blocked vessel

    , Article Journal of Vascular Research ; Volume 56, Issue 6 , 2019 , Pages 296-307 ; 10181172 (ISSN) Saeedi, M ; Shamloo, A ; Mohammadi, A ; Sharif University of Technology
    S. Karger AG  2019
    Abstract
    In this study, using fluid-structure interaction (FSI), 3-dimensional blood flow in an aneurysm in the circle of Willis-which is located in the middle cerebral artery (MCA)-has been simulated. The purpose of this study is to evaluate the effect of a partly blocked vessel on an aneurysm. To achieve this purpose, two cases have been investigated using the FSI method: in the first case, an ideal geometry of aneurysm in the MCA has been simulated; in the second case, modeling is performed for an ideal geometry of the aneurysm in the MCA with a partly blocked vessel. All boundary conditions, properties and modeling methods were considered the same for both cases. The only difference between the... 

    Modeling and simulation of membrane-absorption hybrid systems for CO2 capture from natural gas

    , Article Greenhouse Gas Control Technologies ; 2005 , Pages 2519-2523 ; 9780080447049 (ISBN) Soltanieh, M ; Hojjati Saeedi Saeadi, A ; Sharif University of Technology
    Elsevier Ltd  2005
    Abstract
    Crude (sour) natural gas contains, in addition to CH4 and higher hydrocarbons, various amounts of CO2 and N2, as well as small amounts of gases such as H2S, He, O2, Ar, H2 and H2O vapor. Hybrid systems-that is, membrane for bulk removal of CO2 followed by amine absorption, have been proposed and used since the early 1990s. This chapter focuses on the use of CO2 capture membranes and amine absorption process for CO2 removal from natural gas both as separate processes or a combination of these technologies as hybrid systems. It presents a study in which a rigorous mathematical model for simulation of membrane modules is presented, which utilizes a new model for multi-component gas mixture... 

    Noise canceling balun-LNA with enhanced IIP2 and IIP3 for digital TV applications

    , Article IEICE Transactions on Electronics ; Volume E95-C, Issue 1 , 2012 , Pages 146-154 ; 09168524 (ISSN) Saeedi, S ; Atarodi, M
    2012
    Abstract
    An inductorless low noise amplifier (LNA) with active balun for digital TV (DTV) applications is presented. The LNA exploits a noise cancellation technique which allows for simultaneous wide-band impedance matching and low noise design. The matching and amplifier stages in the LNA topology perform single-ended to differential signal conversion with balanced output. The second and third-order nonlinearity of the individual amplifiers as well as the distortion caused by the interaction between the stages are suppressed to achieve high IIP2 and IIP3. A method for intrinsic cancellation of the second-order interaction is employed to reduce the dependence of the IIP3 on the frequency spacing...