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seyed-shahabadi--mahdi
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High flux electrospun nanofiberous membrane: Preparation by statistical approach, characterization, and microfiltration assessment
, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 59 , 2016 , Pages 474-483 ; 18761070 (ISSN) ; Mousavi, S. A ; Bastani, D ; Sharif University of Technology
Taiwan Institute of Chemical Engineers
2016
Abstract
Preparation, characterization and evaluation of new generation of micro-filters based on polyacrylonitrile electrospun nanofiberous membrane (ENM) were thoroughly investigated. First, quantitative relationships between average diameter, bead area density of nano-fibers and certain electrospinning parameters, i.e., concentration, voltage, spinning distance, and feed rate, were established by empirical modeling based on a central composite design. The analysis revealed that concentration, voltage and distance are the significant parameters. Also, adequacy checking indicated the appropriateness of fit for the models. Afterwards, bead-free ENMs with diameter of 100-500 nm were prepared and...
High flux electrospun nanofiberous membrane: Preparation by statistical approach, characterization, and microfiltration assessment
, Article Revista Mexicana de Urologia ; Volume 76, Issue 1 , 2016 , Pages 474-483 ; 01854542 (ISSN) ; Mousavi, S. A ; Bastani, D ; Sharif University of Technology
Elsevier Doyma Mexico
2016
Abstract
Preparation, characterization and evaluation of new generation of micro-filters based on polyacrylonitrile electrospun nanofiberous membrane (ENM) were thoroughly investigated. First, quantitative relationships between average diameter, bead area density of nano-fibers and certain electrospinning parameters, i.e., concentration, voltage, spinning distance, and feed rate, were established by empirical modeling based on a central composite design. The analysis revealed that concentration, voltage and distance are the significant parameters. Also, adequacy checking indicated the appropriateness of fit for the models. Afterwards, bead-free ENMs with diameter of 100-500 nm were prepared and...
Preparation and Characterization of Electrospun Nanofiberous Membranes for Wastewater Treatment
, M.Sc. Thesis Sharif University of Technology ; Bastani, Daruoosh (Supervisor) ; Moosavi, Ali (Supervisor)
Abstract
The aim of the current project is preparation, characterization and microfiltration evaluation of nanofiberous membrane. In order to prepare membranes, the electrospinning method was utilized and polyacrylonitrile and N-N, dimethylformamide (DMF) were used as the polymer and the solvent, respectively. As the nanofiber diameter controls the structure of the membrane and also bead formation reduces the membrane uniformity, at first the effects of four most influential electrospinning parameters, such as solution concentration, applied voltage, floe rate, and the distance between needle tip and the collector, on average fiber diameter and bead area density were investigated via response surface...
Optimization of operating conditions in ultrafiltration process for produced water treatment via Taguchi methodology
, Article Desalination and Water Treatment ; Volume 54, Issue 10 , June , 2015 ; ISSN: 19443994 ; Sepehrinia, K ; Seyed Shahabadi, S. M ; Rekabdar, F ; Gheshlaghi, A ; Sharif University of Technology
2015
Abstract
This paper describes how to find optimal operating conditions of three controlling parameters, i.e. temperature, transmembrane pressure (TMP), and cross-flow velocity (CFV) for maximizing the permeate flux and total organic carbons (TOC) rejection, and minimizing the fouling resistance using Taguchi method in ultrafiltration (UF) treatment of the real produced water. At first, the optimal operating conditions were found at a temperature of 45°C, TMP = 4 bar, and CFV of 2.25 m/s. To determine the most significant parameters affecting the response parameters, an analysis of variance was employed. In the second stage, performance of applied polymeric membrane in the UF system was studied under...
Optimization of operating conditions in ultrafiltration process for produced water treatment via Taguchi methodology
, Article Desalination and Water Treatment ; Volume 54, Issue 10 , May , 2015 , Pages 2669-2680 ; 19443994 (ISSN) ; Sepehrinia, K ; Seyed Shahabadi, S. M ; Rekabdar, F ; Gheshlaghi, A ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
This paper describes how to find optimal operating conditions of three controlling parameters, i.e. temperature, transmembrane pressure (TMP), and cross-flow velocity (CFV) for maximizing the permeate flux and total organic carbons (TOC) rejection, and minimizing the fouling resistance using Taguchi method in ultrafiltration (UF) treatment of the real produced water. At first, the optimal operating conditions were found at a temperature of 45°C, TMP = 4 bar, and CFV of 2.25 m/s. To determine the most significant parameters affecting the response parameters, an analysis of variance was employed. In the second stage, performance of applied polymeric membrane in the UF system was studied under...
Synthesis of zero-valent iron nanoparticles via electrical wire explosion for efficient removal of heavy metals
, Article Clean - Soil, Air, Water ; Volume 45, Issue 3 , 2017 ; 18630650 (ISSN) ; Rabiee, H ; Seyed Shahabadi, S. M ; Borghei, S. M ; Sharif University of Technology
2017
Abstract
In this paper, electrical wire explosion (EWE) was used as a simple, clean, in situ method to synthesise nano zero-valent iron (nZVI) particles in liquid mediums. The structural and physical properties of the synthesised nZVI particles were characterised by x-ray diffraction, Brunauer–Emmett–Teller analysis, field emission scanning electron microscopy and transmission electron microscopy. The synthesised spherical nanoparticles, at a specific size of 10–50 nm, possessed large surface areas of approximately 13.27 m2/g, reinforcing the significant advantages of EWE, that is, less aggregation and in situ production of nanoparticles with enhanced removal efficacy, for groundwater treatment....
Superhydrophobic dual layer functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PH) nanofibrous membrane for high flux membrane distillation
, Article Journal of Membrane Science ; Volume 537 , 2017 , Pages 140-150 ; 03767388 (ISSN) ; Rabiee, H ; Seyedi, S. M ; Mokhtare, A ; Brant, J. A ; Sharif University of Technology
Elsevier B.V
2017
Abstract
In this study, superhydrophobic dual layer membranes with highly porous structure were fabricated using electrospinning and electrospraying techniques. Electrospinning method was used to produce the support nanofibrous layer using polyvinylidene fluoride-co-hexafluoropropylene (PH) as the polymer and a mixed solvent system of N,N-Dimetylformamide (DMF) and acetone. Afterwards, hydrophobic, functionalized TiO2 nanoparticles were deposited on the surface of the support layer using the electrospraying technique. TiO2 chemical functionalization and their deposition on the support layer were investigated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The...
Order Flow Imbalance Effect on Price Movement in Tehran Stock Exchange
, M.Sc. Thesis Sharif University of Technology ; Barakchian, Mahdi (Supervisor)
Abstract
We investigate order book events impacts on price movement, using the 31 stocks from the Tehran Stock Exchange. We show that in a low-depth market the mid-price change is explained mainly by a linear relationship with our proposed explanatory variable, modified order flow imbalance that represents the depth-adjusted differences of first level orders volumes in different sides of order book. Our results shows that the bid and ask spread has a negative effect on the power of events to move the price
Investigation of Temperature Effect on MOSFET Parameters and Modeling of Carrier Mobility in Temperature Range of 77 - 300K
, M.Sc. Thesis Sharif University of Technology ; Fardmanesh, Mahdi (Supervisor) ; Medi, Ali (Supervisor)
Abstract
Temperature reduction from room temperature to liquid nitrogen temperature has a significant effect in improvement of semiconductor devices operation such as field effect transistors. Nowadays cryoelectronics as a considerable branch of electronics is concerned by several groups. In order to optimize the procedure of low temperature IC design and fabrication we investigated the temperature effects on different parameters of MOSFET in this thesis. Several transistors in a variety of channel lengths were fabricated in different technology files. Wide measurement experiments were done on these transistors in order to find their drain current vs. drain to source voltage characteristics. From...
Machine Learning-Based Positioning in Optical Communication Networks Using a Camera: Indoors and Underwater
, M.Sc. Thesis Sharif University of Technology ; Shabany, Mahdi (Supervisor) ; Hashemi, Matin (Supervisor)
Abstract
Positioning refers to the process of estimating the receiver coordinates aiming for an accurate understanding of the surrounding environment. This branch of science has attracted considerable attention in recent years. Today, the influence sphere of positioning is so expanded that encompasses applications in daily life (e.g., navigation) as well as commercial and even military fields. Global Positioning System (GPS) is the most widely used tool in real-time positioning. Because GPS imposes great measurement errors in challenging conditions (e.g., turbulent water environments), alternative methods such as methods based on Wi-Fi, Bluetooth, and visible light have been proposed. Benefiting...
Investigation of shear lag effect on tension members fillet-welded connections consisting of single and double channel sections
, Article Structural Engineering and Mechanics ; Volume 74, Issue 3 , 2020 , Pages 445-455 ; Maleki, S ; Mirtaheri, M ; Nazeryan, M ; Seyed Mahdi, M. S ; Sharif University of Technology
Techno Press
2020
Abstract
Shear lag phenomenon has long been taken into consideration in various structural codes; however, the AISC provisions have not proposed any specific equation to calculate the shear lag ratio in some cases such as fillet-welded connections of front-to-front double channel sections. Moreover, those equations and formulas proposed by structural codes are based on the studies that were conducted on riveted and bolted connections, and can be applied to single channel sections whilst using them for fillet-welded double channels would be extremely conservative due to the symmetrical shape and the fact that bending moments will not develop in the gusset plate, resulting in less stress concentration....
Analysis of terahertz-induced optical phase modulation in a nonlinear dielectric slab
, Article Progress In Electromagnetics Research M ; Volume 13 , 2010 , Pages 41-51 ; 19378726 (ISSN) ; Izadi, S. A ; Shahabadi, M ; Sharif University of Technology
2010
Abstract
Frequency shift of the spectrum of an incident optical pulse by an intense THz pulse inducing cross-phase modulation (XPM) in a nonlinear dielectric slab is analyzed. The effect is predicted with a high degree of accuracy using the well-known transmission line matrix (TLM) technique. In this research, to model the THz-induced temporal and spatial variation of the dielectric permittivity of the nonlinear dielectric slab, the transmission lines of the TLM method are loaded with open shunt stubs. The parameters of the stubs are modified in accordance with the refractive index variation of the dielectric slab, here ZnTe, induced by the strong THz pulse. The obtained numerical results are...
Extremely Emissive V-Grooved Microstructure Made of SU-8 for Enhanced Radiative Cooling
, Article IEEE Photonics Journal ; Volume 15, Issue 4 , 2023 ; 19430655 (ISSN) ; Badieirostami, M ; Shahabadi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2023
Abstract
For a structure to show radiative cooling property, it must have first, high reflectivity of above 90% in the wavelength range of 0.3 to 3 μm, and second, high emissivity for the wavelengths ranging from 8 to 13 μm, namely atmospheric transparency window. Being inspired by the architecture of microwave absorbers used extensively for antenna measurements, we proposed a novel microstructure with near unity emissivity that can be further developed for radiative cooling. To this end, we designed and analyzed a V-grooved multilayer periodic microstructure capable of perfectly emitting in the aforementioned wavelength range. Further, SU-8 is selected as the material of the proposed microstructure....
Design of a wideband terahertz absorber composed of graphene patches
, Article IET Optoelectronics ; Volume 13, Issue 5 , 2019 , Pages 235-239 ; 17518768 (ISSN) ; Maddahali, M ; Bakhtafrouz, A ; Shahabadi, M ; Sharif University of Technology
Institution of Engineering and Technology
2019
Abstract
Here, the design of a wideband absorber operating at terahertz frequencies is presented. The design is based on an analytical circuit model of graphene arrays of rectangular patches obtained from the presented circuit model of graphene arrays of disks. A recently proposed method is generalised for the design of wideband absorbers at higher frequencies The bandwidth is increased by correct tuning of the input impedance for a structure composed of two layers of graphene arrays and a metal-backed dielectric layer. Using two-layer graphene arrays, the authors decrease the slope of the imaginary part of the input impedance to increase the bandwidth. The designed absorber works at a frequency of...
Spurious-free analysis of two-dimensional low-loss metallic gratings
, Article Journal of Optics (United Kingdom) ; Volume 18, Issue 3 , 2016 ; 20408978 (ISSN) ; Nezhad, A. Z ; Borji, A ; Shahabadi, M ; Sharif University of Technology
Institute of Physics Publishing
2016
Abstract
Transmission line formulation is used to analyze two-dimensional low-loss metallic gratings at optical frequencies when plasmonic waves propagate in the structure. This method, like the Fourier modal method, suffers from numerical instabilities when applied to such structures. A systematic approach to avoid these instabilities is presented. These numerical artifacts are attributed to the violation of Li's inverse rule and the appearance of higher-order spurious modes. In this paper, a new approach is proposed to identify and to greatly reduce the effect of these spurious modes based on the accuracy by which these modes are satisfying the conservation of momentum. Furthermore, the proposed...
Improved fourier analysis of periodically patterned graphene sheets embedded in multilayered structures and its application to the design of a broadband tunable wide-angle polarizer
, Article IEEE Journal of Quantum Electronics ; Volume 53, Issue 3 , 2017 ; 00189197 (ISSN) ; Borji, A ; Zeidaabadi Nezhad, A ; Shahabadi, M ; Sharif University of Technology
2017
Abstract
Numerical modeling of periodically patterned graphene sheets (PPGS) embedded in planar multilayered media using Fourier-based methods suffers from very slow convergence because of the fact that the conductivity is zero in unfilled areas of the patterned surface and, thus, the so-called Li's inverse rule is not applicable. In this paper, a simple and efficient approach is proposed to overcome this problem such that the exact boundary condition can be applied and the surface current density on PPGS can be obtained accurately. Here, the PPGS is modeled as a conductive surface and only its conductivity representation by the Fourier series is modified. The proposed method can be used easily for...
Stanley depth of the integral closure of monomial ideals
, Article Collectanea Mathematica ; Volume 64, Issue 3 , November , 2013 , Pages 351-362 ; 00100757 (ISSN) ; Sharif University of Technology
2013
Abstract
Let I be a monomial ideal in the polynomial ring S=K [x1,... xn]. We study the Stanley depth of the integral closure Ī of I. We prove that for every integer k ≥ 1, the inequalities (S/Ik) ≤ sdepth (S/Ī) and sdepth(Ik) ≤ sdepth(Ī) hold. We also prove that for every monomial ideal I⊂ S there exist integers k1,k2≥ 1, such that for every s≥ 1, the inequalities sdepth (S/Isk1) ≤ sdepth(S/Ī) and sdepth (Isk2) ≤ sdepth (Ī) hold. In particular, mink{sdepth(S/Ik)} ≤ sdepth(S/Ī) and min̄k {sdepth (Ik)}≤ sdepth(Ī). We conjecture that for every integrally closed monomial ideal I, the inequalities sdepth(S/I)≥ n-l (I) and sdepth (I)≥ n-l (I)+1 hold, where l (I) is the analytic spread of I. Assuming the...
Dynamic modeling and sensitivity analysis of atomic force microscope pushing force in nanoparticle manipulation on a rough substrate [electronic resource]
, Article Journal of Advanced Science, Engineering and Medicine ; 2013, Vol. 5, pp. 1-10 ; Mahboobi, Seyed Hanif ; Meghdari, Ali ; Sharif University of Technology
Abstract
An Atomic Force Microscope (AFM) is a capable tool to manipulate nanoparticles by exerting pushing force on the nanoparticles located on the substrate. In reality, the substrate cannot be considered as a smooth surface particularly at the nanoscale. Hence, the particle may encounter a step on the substrate during a manipulation. In this study, dynamics of the nanoparticle on a stepped substrate and critical pushing force in the manipulation are investigated. There are two possible dynamic modes that may happen in the manipulation on the stepped substrate. In one mode, the nanoparticle may slide on the step edge and then climb up to the step which is a desired mode. Another possible mode is...
MBBR and MBR Reactor Configuration for Better Performance
, M.Sc. Thesis Sharif University of Technology ; Borgheei, Mahdi (Supervisor)
Abstract
Membrane bioreactors (MBRs) which are commonly understood as the combination of membrane filtration and biological treatment using activated sludge have several advantages, but membrane fouling reduces the membrane efficiency, permeability and lifetime. An alternative is replacing a moving bed biofilm reactor (MBBR) with the activated sludge system which may reduce the effect of membrane fouling. The sludge produced in MBBRs has poor settling characteristics, therefore, their efficiency is limited by the sedimentation tank performance and they require a larger settling surface. The combination of moving bed biofilm reactors and membrane bioreactors can compensate for the drawbacks of both of...
Simulation of static recrystallization in non-isothermal annealing using a coupled cellular automata and finite element model
, Article Computational Materials Science ; Volume 53, Issue 1 , 2012 , Pages 145-152 ; 09270256 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
2012
Abstract
A coupled cellular automata and finite element model has been proposed to evaluate static recrystallization kinetics during non-isothermal annealing of cold deformed low carbon steels. The effects of various factors including heating rate, annealing temperature, and initial microstructures have been considered in the model to accurately predict the static recrystallization kinetics and the final microstructures. In order to examine the employed algorithm, the predicted results have been compared with the experimental observations and a good agreement was found between the two sets of results