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    Large deformation finite element modeling of rubble mound breakwater built on soft seabed using coupled eulerian–lagrangian method

    , Article Indian Geotechnical Journal ; Volume 51, Issue 2 , 2021 , Pages 315-328 ; 09719555 (ISSN) Masoudi, S ; Shahir, H ; Pak, A ; Sharif University of Technology
    Springer  2021
    Abstract
    For the design of rubble mound breakwaters on soft soil, it is essential to predict the behavior of soft soil and large deformations phenomena occurring in the course of construction of the rubble mound breakwater. Large deformations in various problems can be well simulated using the coupled Eulerian–Lagrangian (CEL) method. In this study, the CEL method has been used to simulate the rubble mounds construction on soft soil and predict the resulting settlements. To validate the numerical model, the results of three experiments conducted in the physical modeling laboratory at Kharazmi University were used. Also, two case studies of real rubble mound breakwaters constructed on soft seabeds... 

    A new approach for touching cells segmentation

    , Article BioMedical Engineering and Informatics: New Development and the Future - 1st International Conference on BioMedical Engineering and Informatics, BMEI 2008, Sanya, Hainan, 27 May 2008 through 30 May 2008 ; Volume 1 , 2008 , Pages 816-820 ; 9780769531182 (ISBN) Nasr Isfahani, S ; Mirsafian, A ; Masoudi Nejad, A ; Sharif University of Technology
    2008
    Abstract
    Automatic cell segmentation has various applications in different parts of science. The development of automated methods for cell segmentation, remains challenging in situations where there are touching cells. In this paper we propose a new method for separating touching cells. As the first step, we use a combination of graph segmentation algorithm and thresholding for segmenting foreground objects and producing a binary image. Next, boundary points of separation zone are selected by using a corner detection algorithm. Finally, the marker controller watershed transform is applied to separate touching cells at selected points. © 2008 IEEE  

    Level crossing analysis of Burgers equation in 1 + 1 dimensions

    , Article Journal of Physics A: Mathematical and General ; Volume 39, Issue 15 , 2006 , Pages 3903-3909 ; 03054470 (ISSN) Movahed, M. S ; Bahraminasab, A ; Rezazadeh, H ; Masoudi, A. A ; Sharif University of Technology
    2006
    Abstract
    We investigate the average frequency of positive slope ν +α, crossing the velocity field in the Burgers equation. The level crossing analysis in the inviscid limit and the total number of positive crossings of the velocity field before the creation of singularities are given. The main goal of this paper is to show that this quantity, ν+α, is a good measure for the fluctuations of velocity fields in the Burgers turbulence. © 2006 IOP Publishing Ltd  

    Avrami behavior of magnetite nanoparticles formation in co-precipitation process

    , Article Journal of Mining and Metallurgy, Section B: Metallurgy ; Volume 47, Issue 2 , 2011 , Pages 211-218 ; 14505339 (ISSN) Ahmadi, R ; Hosseini, H. M. R ; Masoudi, A ; Sharif University of Technology
    2011
    Abstract
    In this work, magnetite nanoparticles (mean particle size about 20 nm) were synthesized via coprecipitation method. In order to investigate the kinetics of nanoparticle formation, variation in the amount of reactants within the process was measured using pH-meter and atomic absorption spectroscopy (AAS) instruments. Results show that nanoparticle formation behavior can be described by Avrami equations. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were performed to study the chemical and morphological characterization of nanoparticles. Some simplifying assumptions were employed for estimating the nucleation and growth rate of magnetite nanoparticles  

    Using three-dimensional finite element analysis for simulation of residual stresses in railway wheels

    , Article Engineering Failure Analysis ; Vol. 45, issue , October , 2014 , p. 449-455 Masoudi Nejad, R ; Sharif University of Technology
    2014
    Abstract
    One of the most important issues in railway wheels is residual stresses. It is desirable to produce less residual stresses when possible and to decrease the remaining residual stresses in the wheels. The objective of this paper is to provide an estimation of the residual stresses in the rail wheel caused by the stress field from heat treatment process of a railway wheel. A three-dimensional nonlinear stress analysis model has been applied to estimate stress fields of the railway mono-block wheel in heat treatment process. After forging or casting, railway wheels are heat-treated to induce the desirable circumferential compressive residual stress in the upper rim. Finite element analysis... 

    Expectation propagation for large scale Bayesian inference of non-linear molecular networks from perturbation data

    , Article PloS one ; Volume 12, Issue 2 , 2017 , Pages e0171240- ; 19326203 (ISSN) Narimani, Z ; Beigy, H ; Ahmad, A ; Masoudi Nejad, A ; Fröhlich, H ; Sharif University of Technology
    2017
    Abstract
    Inferring the structure of molecular networks from time series protein or gene expression data provides valuable information about the complex biological processes of the cell. Causal network structure inference has been approached using different methods in the past. Most causal network inference techniques, such as Dynamic Bayesian Networks and ordinary differential equations, are limited by their computational complexity and thus make large scale inference infeasible. This is specifically true if a Bayesian framework is applied in order to deal with the unavoidable uncertainty about the correct model. We devise a novel Bayesian network reverse engineering approach using ordinary... 

    Genome-wide DNA methylation profiling in ectopic and eutopic of endometrial tissues

    , Article Journal of Assisted Reproduction and Genetics ; Volume 36, Issue 8 , 2019 , Pages 1743-1752 ; 10580468 (ISSN) Barjaste, N ; Shahhoseini, M ; Afsharian, P ; Sharifi Zarchi, A ; Masoudi Nejad, A ; Sharif University of Technology
    Springer New York LLC  2019
    Abstract
    Purpose: Endometriosis is a gynecological disease that causes the uterine lining to appear in other organs outside the uterus. As DNA methylation has an important role in this disorder, its profiling can reveal new information to improve the diagnosis and treatment of endometriosis patients. Methods: We conducted a genome-wide methylation profiling of ectopic and eutopic endometrial tissues from women with and without endometriosis using Infinium Human Methylation 450K BeadChip arrays. DNA methylation samples were collected from nine ectopic and nine eutopic endometrial tissues of endometriosis and six endometrial tissues of healthy controls. Results: Correlation heatmaps and the principal... 

    Topological spin liquids in the ruby lattice with anisotropic Kitaev interactions

    , Article Physical Review B - Condensed Matter and Materials Physics ; Volume 94, Issue 12 , 2016 ; 10980121 (ISSN) Jahromi, S. S ; Kargarian, M ; Masoudi, S. F ; Langari, A ; Sharif University of Technology
    American Physical Society  2016
    Abstract
    The ruby lattice is a four-valent lattice interpolating between honeycomb and triangular lattices. In this work we investigate the topological spin-liquid phases of a spin Hamiltonian with Kitaev interactions on the ruby lattice using exact diagonalization and perturbative methods. The latter interactions combined with the structure of the lattice yield a model with Z2×Z2 gauge symmetry. We mapped out the phase diagram of the model and found gapped and gapless spin-liquid phases. While the low-energy sector of the gapped phase corresponds to the well-known topological color code model on a honeycomb lattice, the low-energy sector of the gapless phases is described by an effective spin model... 

    Exact analysis of level-crossing statistics for (d+1)-dimensional fluctuating surfaces

    , Article Journal of Statistical Physics ; Volume 124, Issue 6 , 2006 , Pages 1471-1490 ; 00224715 (ISSN) Bahraminasab, A ; Movahed, M. S ; Nasiri, S. D ; Masoudi, A. A ; Sahimi, M ; Sharif University of Technology
    2006
    Abstract
    We carry out an exact analysis of the average frequency ν+ αxi in the direction x i of positiveslope crossing of a given level α such that, h(x, t) h = α, of growing surfaces in spatial dimension d. Here, h(x, t) is the surface height at time t, and h is its mean value. We analyze the problem when the surface growth dynamics is governed by the Kardar-Parisi-Zhang (KPZ) equation without surface tension, in the time regime prior to appearance of cusp singularities (sharp valleys), as well as in the random deposition (RD) model. The total number N + of such level-crossings with positive slope in all the directions is then shown to scale with time as t d/2 for both the KPZ equation and the RD... 

    Zero tension Kardar-Parisi-Zhang equation in (d + 1)-dimensions

    , Article Journal of Statistical Physics ; Volume 116, Issue 5-6 , 2004 , Pages 1521-1544 ; 00224715 (ISSN) Bahraminasab, A ; Tabei, S. M. A ; Masoudi, A. A ; Shahbazi, F ; Rahimi Tabar, M. R ; Sharif University of Technology
    2004
    Abstract
    The joint probability distribution function (PDF) of the height and its gradients is derived for a zero tension d + 1-dimensional Kardar-Parisi-Zliang (KPZ) equation. It is proved that the height's PDF of zero tension KPZ equation shows lack of positivity after a finite time tc. The properties of zero tension KPZ equation and its differences with the case that it possess an infinitesimal surface tension is discussed. Also potential relation between the time scale tc and the singularity time scale tc,v→0 of the KPZ equation with an infinitesimal surface tension is investigated. © 2004 Springer Science+Business Media, Inc  

    Automated Plant Species Identification Using Leaf Shape-Based Classification Techniques: A Case Study on Iranian Maples

    , Article Iranian Journal of Science and Technology - Transactions of Electrical Engineering ; Volume 45, Issue 3 , 2021 , Pages 1051-1061 ; 22286179 (ISSN) Mohtashamian, M ; Karimian, M ; Moola, F ; Kavousi, K ; Masoudi Nejad, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    Foliar characteristics, especially the overall leaf shape, are useful features for the taxonomic identification of plants. Computer-aided plant species identification systems make it possible to investigate a large number of leaves in a short period of time. In this study, a fully automatic system was developed to accurately classify eight species of maples (Acer L.) in Iran using the leaf shape characteristics of harvested leaves. Maples show a broad range of leaf morphology, and the provided dataset is a diverse collection of simple leaves which can be a good representative of woody plant leaves with any overall shape and margin pattern. The applied method consisted of preprocessing,... 

    Statistical theory for the Kardar-Parisi-Zhang equation in (1+1) dimensions

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 65, Issue 2 , 2002 , Pages 026132/1-026132/22 ; 15393755 (ISSN) Masoudi, A. A ; Shahbazi, F ; Davoudi, J ; Rahimi Tabar, M. R ; Sharif University of Technology
    2002
    Abstract
    The Kardar-Parisi-Zhang (KPZ) equation in (1 + 1) dimensions dynamically develops sharply connected valley structures within which the height derivative is not continuous. We develop a statistical theory for the KPZ equation in (1 + 1) dimensions driven with a random forcing that is white in time and Gaussian-correlated in space. A master equation is derived for the joint probability density function of height difference and height gradient P(h-h̄,∂xh,t) when the forcing correlation length is much smaller than the system size and much larger than the typical sharp valley width. In the time scales before the creation of the sharp valleys, we find the exact generating function of h-h̄ and ∂xh.... 

    Statistical theory for the Kardar-Parisi-Zhang equation in [formula presented] dimensions

    , Article Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics ; Volume 65, Issue 2 , 2002 ; 1063651X (ISSN) Masoudi, A. A ; Shahbazi, F ; Davoudi, J ; Rahimi Tabar, M. R ; Sharif University of Technology
    2002
    Abstract
    The Kardar-Parisi-Zhang (KPZ) equation in [formula presented] dimensions dynamically develops sharply connected valley structures within which the height derivative is not continuous. We develop a statistical theory for the KPZ equation in [formula presented] dimensions driven with a random forcing that is white in time and Gaussian-correlated in space. A master equation is derived for the joint probability density function of height difference and height gradient [formula presented] when the forcing correlation length is much smaller than the system size and much larger than the typical sharp valley width. In the time scales before the creation of the sharp valleys, we find the exact... 

    The effect of poly(ethylene glycol) coating on colloidal stability of superparamagnetic iron oxide nanoparticles as potential MRI contrast agent

    , Article International Journal of Pharmaceutics ; Volume 433, Issue 1-2 , 2012 , Pages 129-141 ; 03785173 (ISSN) Masoudi, A ; Madaah Hosseini, H. R ; Shokrgozar, M. A ; Ahmadi, R ; Oghabian, M. A ; Sharif University of Technology
    2012
    Abstract
    Superparamganetic iron oxide-based contrast agents in magnetic resonance imaging (MRI) have offered new possibility for early detection of lymph nodes and their metastases. According to important role of nanoparticle size in biodistribution, magnetite nanoparticles coated with different polyethylene glycol (PEG) concentrations up to 10/1 PEG/iron oxide weight ratio in an ex situ manner. To predict the PEG-coated nanoparticle behavior in biological media, such as blood stream or tissue, colloidal stability evaluation was performed to estimate the coating endurance in different conditions. Accordingly, optical absorbance measurements were conducted in solutions with different values of pH and... 

    Intermittency of height fluctuations in stationary state of the Kardar-Parisi-Zhang equation with infinitesimal surface tension in 1+1 dimensions

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 70, Issue 3 1 , 2004 , Pages 031101-1-0311011-3 ; 15393755 (ISSN) Tabei, S. M. A ; Bahraminasab, A ; Masoudi, A. A ; Mousavi, S. S ; Tabar, M. R. R ; Sharif University of Technology
    2004
    Abstract
    Intermittency of height fluctuations in stationary state of the Kardar-Parisi-Zhang (KPZ) equation with infinitesimal surface tension in 1+1 dimensions was discussed. Stochastic differential equations were used for the study. It was found that the probability density function [in 1+1] is independent of the coefficient of the linear term. When the random force with smooth spatial correlation was considered, the problem changed to a more complicated one  

    Intermittency of height fluctuations in stationary state of the Kardar-Parisi-Zhang equationwith infinitesimal surface tension in [Formula presented] dimensions

    , Article Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics ; Volume 70, Issue 3 , 2004 , Pages 13- ; 1063651X (ISSN) Tabei, S. M. A ; Bahraminasab, A ; Masoudi, A. A ; Mousavi, S. S ; Reza Rahimi Tabar, M ; Sharif University of Technology
    2004
    Abstract
    The Kardar-Parisi-Zhang (KPZ) equation with infinitesimal surface tension, dynamically develops sharply connected valley structures within which the height derivative is not continuous. We discuss the intermittency issue in the problem of stationary state forced KPZ equation in [Formula presented] dimensions. It is proved that the moments of height increments [Formula presented] behave as [Formula presented] with [Formula presented] for length scales [Formula presented]. The length scale [Formula presented] is the characteristic length of the forcing term. We have checked the analytical results by direct numerical simulation. © 2004 The American Physical Society  

    Evaluating the effect of ultrasmall superparamagnetic iron oxide nanoparticles for a long-term magnetic cell labeling

    , Article Journal of Medical Physics ; Volume 38, Issue 1 , 2013 , Pages 34-40 ; 09716203 (ISSN) Shanehsazzadeh, S ; Oghabian, M. A ; Allen, B. J ; Amanlou, M ; Masoudi, A ; Daha, F. J ; Sharif University of Technology
    2013
    Abstract
    In order to evaluate the long-term viability, the iron content stability, and the labeling efficiency of mammalian cells using magnetic cell labeling; dextran-coated ultrasmall superparamagnetic iron oxide (USPIOs) nanoparticles with plain surfaces having a hydrodynamic size of 25 nm were used for this study. Tests were carried out in four groups each containing 5 flasks of 5.5 × 10 6 AD-293 embryonic kidney cells. The cell lines were incubated for 24 h using four different iron concentrations with and without protamine sulfate (Pro), washed with phosphate-buffered saline (PBS) and centrifuged three times to remove the unbounded USPIOs. Cell viability was also verified using USPIOs. There... 

    Rolling Contact Fatigue under Influence of Residual Stresses

    , M.Sc. Thesis Sharif University of Technology Masoudi Nejad, Reza (Author) ; Farahi, Gholamhossin (Supervisor)
    Abstract
    Rolling contact fatigue (RCF) phenomena is important in reducing the fatigue life and increasing the cost of maintenance. Accurate prediction of crack growth on wheels and the influence of residual stresses by FEM modeling can affect the maintenance planning. Therefore, investigation of rolling contact fatigue and its effect on rolling members life seem necessary. The first step to solve a rolling contact fatigue problem is the residual stress determination. In this research, wheel/rail contact is assumed. A bandage wheel with accurate geometry using finite element method is studied. For this purpose, a 3D elastic-plastic finite element model in ANSYS is conducted using model. The... 

    The Impact of Temperature on Surface Activity and Stability of Surface Modified Nano Particles

    , M.Sc. Thesis Sharif University of Technology Masoudi, Ghasem (Author) ; Mohammadi, Ali Asghar (Supervisor)
    Abstract
    Surface modification is an important property of nano particles. In this project surface of silica nano particles modified with hydrophobic and hydrophilic groups to imrprove surface activity of nano particles. Purpose of this project is to study surface activity of surface modified silica nano particles in different temperatures from 20 to 70 degree centigrade. Also effect of salt and time on the surface activity is studied. At first nano particles modified just with haydrophobic groups and then just with hydrophilic groups (hydrophobic and hydrophilic nano particles) and after that, the surface modification done with both hyadrophilic and hydrophobic groups (amphiphilic nanoparticles).... 

    Power quality survey in a distribution system, standard procedures and limitations

    , Article Renewable Energy and Power Quality Journal ; Volume 1, Issue 5 , 2007 , Pages 460-464 ; 2172038X (ISSN) Mokhtari, H ; Hasani, S ; Masoudi, M ; Sharif University of Technology
    European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ)  2007
    Abstract
    This paper presents the results of a power quality survey in a distribution system. More than fifty nodes are selected and monitored. Power quality indices are extracted based on IEEE and IEC Standards. The evaluation includes field data collection, extraction of statistical power quality indices and comparing the results against standard limits. Experimental data as well as clarifying tables and graphs are presented. The results are then discussed to evaluate the strength and weaknesses of applying standard limits when real observations are to be performed. Some proposals are also made in order to make standard procedures and limits more effective based on practical observations. © 2007,...