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Fracture analysis of monolayer graphene sheets with double vacancy defects via MD simulation
, Article Solid State Communications ; Volume 151, Issue 17 , 2011 , Pages 1141-1146 ; 00381098 (ISSN) ; Motevalli, B ; Montazeri, A ; Ajori, S ; Sharif University of Technology
2011
Abstract
Carbon nanostructures such as carbon nanotubes (CNTs) and graphene sheets have attracted great attention due to their exceptionally high strength and elastic strain. These extraordinary mechanical properties, however, can be affected by the presence of defects in their structures. When a material contains multiple defects, it is expected that the stress concentration of them superposes if the separation distances of the defects are low, which causes a more reduction of the strength. On the other hand, it is believed that if the defects are far enough such that their affected areas are distinct, their behavior is similar to a material with single defect. In this article, molecular dynamics...
Protein corona impact on nanoparticle-cell interactions: Toward an energy-based model of endocytosis
, Article Journal of Physics Condensed Matter ; Volume 32, Issue 11 , 2020 ; Mehrafrooz, B ; Montazeri, A ; Naghdabadi, R ; Sharif University of Technology
Institute of Physics Publishing
2020
Abstract
Upon incubation of nanoparticles in biological fluids, a new layer called the protein corona is formed on their surface affecting the interactions between nanoparticles and targeted cells during the endocytosis process. In the present study, a mathematical model based on the diffusion of membrane mobile receptors is proposed. Opposing the endocytosis proceeding, membrane bending and tension energies are named as resistant energy. Also, the binding energy and free-energy associated with the configurational entropy are collectively termed promoter energy. Utilizing this model, endocytosis of gold nanoparticle (GNP) is simulated to explore the biological media effect. The results reveal that...
Translation and validation of the Persian version of the Arthritis Impact Measurement Scales 2-Short Form (AIMS2-SF) in patients with rheumatoid arthritis
, Article Clinical Rheumatology ; Volume 28, Issue 5 , 2009 , Pages 521-527 ; 07703198 (ISSN) ; Mousavi, S. J ; Parnianpour, M ; Montazeri, A ; Sharif University of Technology
2009
Abstract
Cultural adaptation and validation of the Persian version of the Arthritis Measurement Scales 2-Short Form (AIMS2-SF). The translation and cultural adaptation of the original questionnaire was carried out in accordance with published guidelines. Three hundred and fifty consecutive Persian-speaking patients with rheumatoid arthritis (RA) were asked to complete the AIMS2-SF, the Short Form Health Survey (SF-36), and four visual analog scales (VAS) for pain, joint stiffness, and patient's and physician's global assessment to test convergent validity. In addition, 90 randomly selected patients were asked to complete the questionnaire 48 h later for the second time. Moderate to high correlation...
Cultural adaptation and validation of the persian version of the arthritis impact measurement scales 2-short form in patients with osteoarthritis of the knee
, Article Disability and Rehabilitation ; Volume 31, Issue 25 , 2009 , Pages 2081-2087 ; 09638288 (ISSN) ; Mousavi, J ; Montazeri, A ; Shamsollahi, S ; Parnianpour, M ; Sharif University of Technology
2009
Abstract
Purpose.To translate and validate the Persian version of the Arthritis Measurement Scales 2-Short Form (AIMS2-SF) in patients with osteoarthritis (OA) of the knee. Method.The translation and cultural adaptation of the original questionnaire was carried out in accordance with published guidelines. One hundred and fourteen consecutive Persian-speaking patients with OA of the knee were participated in this study. The Short Form Health Survey (SF-36) and visual analogue scales (VAS) for pain and joint stiffness were used to test convergent validity of the Persian AIMS2-SF. In addition, 35 randomly selected patients were asked to complete the questionnaire 3 days later for the second time....
Experimental investigation of asphaltene content effect on crude oil/co2 minimum miscibility pressure
, Article Periodica Polytechnica Chemical Engineering ; Volume 64, Issue 4 , 2020 , Pages 479-490 ; Gandomkar, A ; Montazeri, G ; Honarvar, B ; Azdarpour, A ; Rezaee, M ; Sharif University of Technology
Budapest University of Technology and Economics
2020
Abstract
Minimum Miscibility Pressure (MMP) is regarded as one of the foremost parameters required to be measured in a CO2 injection process. Therefore, a reasonable approximation of the MMP can be useful for better development of injection conditions as well as planning surface facilities. In this study, the impact of asphaltene content ranging from 3.84 % to 16 % on CO2/heavy oil MMP is evaluated. In this respect, slim tube miscibility and Vanishing Interfacial Tension (VIT) tests are used. Regarding the VIT test, the Interfacial Tension (IFT) is measured by means of two methods including pendant drop and capillary apparatuses, and thereafter the MMP measurement error between slim tube and VIT...
Investigation of the interphase effects on the mechanical behavior of carbon nanotube polymer composites by multiscale modeling
, Article Journal of Applied Polymer Science ; Volume 117, Issue 1 , March , 2010 , Pages 361-367 ; 00218995 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2010
Abstract
In this article, a multiscale modeling procedure is implemented to study the effect of interphase on the Young's modulus of CNT/polymer composites. For this purpose, a three-phase RVE is introduced which consists of three components, i.e., a carbon nanotube, an interphase layer, and an outer polymer matrix. The nanotube is modeled at the atomistic scale using molecular structural mechanics. Moreover, three-dimensional elements are employed to model the interphase layer and polymer matrix. The nanotube and polymer matrix are assumed to be bonded by van der Waals interactions based on the Lennard-Jones potential at the interface. Using this Molecular Structural Mechanics/Finite Element...
Study the effect of viscoelastic matrix model on the stability of CNT/polymer composites by multiscale modeling
, Article Polymer Composites ; Volume 30, Issue 11 , 2009 , Pages 1545-1551 ; 02728397 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2009
Abstract
In this article, a Molecular Structural Mechanics/Finite Element (MSM/FE) multiscale modeling of carbon nanotube/polymer composites with viscoelastic (VE) polymer matrix is introduced. The nanotube is modeled at the atomistic scale using structural molecular mechanics. The matrix deformation is analyzed by nonlinear finite element method considering VE behavior. The nanotube and matrix are assumed to be bonded by van der Waals interactions based on the Lennard-Jones potential at the interface. Using the MSM/FE multiscale model, we investigate the effect of carbon nanotube (CNT) on the improvement of mechanical stability of the nanocomposite. Also, the buckling behavior of these...
Investigating the effect of carbon nanotube defects on the column and shell buckling of carbon nanotube-polymer composites using multiscale modeling
, Article International Journal for Multiscale Computational Engineering ; Volume 7, Issue 5 , 2009 , Pages 431-444 ; 15431649 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2009
Abstract
Carbon nanotube (CNT)-reinforced polymer composites have attracted great attention due to their exceptionally high strength. Their high strength can be affected by the presence of defects in the nanotubes used as reinforcements in practical nanocomposites. In this article, a new three-phase molecular structural mechanics/finite element (MSM/FE) multiscale model is used to study the effect of CNT vacancy defects on the stability of single-wall (SW) CNT-polymer composites. The nanotube is modeled at the atomistic scale using MSM, whereas the interphase layer and polymer matrix are analyzed by the FE method. The nanotube and polymer matrix are assumed to be bonded by van der Waals interactions...
Controller Design for Nonlinear fractional Order Systems in the Presence of Input and Output Constraints
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
The purpose of this thesis is design of an adaptive tracking control for input-quantized strict-feedback fractional order nonlinear systems with unknown dynamics and asymmetric time-varying output constraints. The controller design is achieved by using a hysteretic quantizer to avoid chattering and not needing the quantization parameters. The fuzzy logic method has been used to solve the problem of unknown dynamics. Also, due to the asymmetric time-varying output constraints, the Barrier Lyapunov function has been used. In this thesis, less restrictive assumptions have been considered than the work performed in previous researches.By utilizing the adaptive backstepping approach and based on...
Investigation the stability of SWCNT-polymer composites in the presence of CNT geometrical defects using multiscale modeling
, Article 4th International Conference on Multiscale Materials Modeling, MMM 2008, 27 October 2008 through 31 October 2008 ; 2008 , Pages 163-166 ; 9780615247816 (ISBN) ; Naghdabadi, R ; Sharif University of Technology
Department of Scientific Computing, Florida State University
2008
Abstract
CNT-reinforced polymer composites have attracted attention due to their exceptional high strength. The high strength can be affected by the presence of defects in the nanotubes used as reinforcements in the practical nanocomposites. In this paper, a Molecular Structural Mechanics / Finite Element (MSM/FE) multiscale modeling is used to study the effect of carbon nanotube geometrical defects on the stability of SWCNT-polymer composites. Here, two types of representative volume elements (RVEs) for these nanocomposites are considered with perfect and defected CNT. These RVEs have the same dimensions. The nanotube is modeled at the atomistic scale using molecular structural mechanics whereas the...
Paroxysmal atrial fibrillation prediction using Kalman filter
, Article ACM International Conference Proceeding Series, 26 October 2011 through 29 October 2011, Barcelona ; 2011 ; 9781450309134 (ISBN) ; Shamsollahi, M. B ; Carrault, G ; Hernández, A. I ; Sharif University of Technology
2011
Abstract
In this paper, we proposed a method based on Kalman Filter for predicting the onset of paroxysmal atrial fibrillation (PAF) from the electrocardiogram (ECG) using clinical data available from the Computers in Cardiology (CinC) Challenge 2001. To predict PAF, we developed an algorithm based upon the number of atrial premature complexes (APCs) in the ECG. The algorithm detects classical isolated APCs by monitoring fidelity signals, which is defined here as a function of the innovation signal of Kalman filter, in vicinity of premature heartbeats and decides whether one beat is APC or not then predicts PAF, based on the number of APC. The challenge database consists of 56 pairs of 30-minute ECG...
Mapping state diagram to petri net : An approach to use markov theory for analyzing non-functional parameters
, Article 2006 International Conference on Systems, Computing Sciences and Software Engineering, SCSS 2006, Part of the International Joint Conferences on Computer, Information, and Systems Sciences, and Engineering, CISSE 2006, 4 December 2006 through 14 December 2006 ; 2007 , Pages 185-190 ; 9781402062636 (ISBN) ; Siasifar, M ; Montazeri, H ; Movaghar, A ; Zandakbari, M ; Sharif University of Technology
2007
Abstract
The quality of an architectural design of a software system has a great influence on achieving nonfunctional requirements to the system. Unified Modeling Language (UML), which is the industry standard as a common object oriented modeling language needs a well-defined semantic base for its notation. Integrating formal methods Petri nets (PNs) with object oriented design concepts UML is useful to benefit from the strengths of both approaches. Formalization of the graphical notation enables automated processing and analysis tasks. In this paper we use a method to converting State Diagram to Generalized Stochastic Petri Net (GSPN) and then we derive the embedded Continues Time Markov Chain from...
The Oswestry Disability Index, the Roland-Morris Disability Questionnaire, and the Quebec Back Pain Disability Scale: Translation and validation studies of the Iranian versions
, Article Spine ; Volume 31, Issue 14 , 2006 , Pages E454-E459 ; 03622436 (ISSN) ; Parnianpour, M ; Mehdian, H ; Montazeri, A ; Mobini, B ; Sharif University of Technology
2006
Abstract
STUDY DESIGN. Cross-cultural translation and psychometric testing were performed. OBJECTIVES. To cross-culturally translate the Oswestry Disability Index (ODI), Roland-Morris Disability Questionnaire (RDQ), and Quebec Back Pain Disability Scale (QDS) into Persian, and then investigate the psychometric properties of the Persian versions produced. SUMMARY OF BACKGROUND DATA. To the authors' knowledge, there is no validated instrument to measure functional status in Persian-speaking patients with low back pain (LBP) in Iran. To our knowledge, the widely used back-specific measures, the ODI, RDQ, and QDS, have not been translated and validated for Persian-speaking patients with LBP. METHODS. The...
Apnea bradycardia detection based on new coupled hidden semi Markov model
, Article Medical and Biological Engineering and Computing ; 12 November , 2020 ; Shamsollahi, M. B ; Ge, D ; Beuchee, A ; Hernandez, A. I ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2020
Abstract
In this paper, a method for apnea bradycardia detection in preterm infants is presented based on coupled hidden semi Markov model (CHSMM). CHSMM is a generalization of hidden Markov models (HMM) used for modeling mutual interactions among different observations of a stochastic process through using finite number of hidden states with corresponding resting time. We introduce a new set of equations for CHSMM to be integrated in a detection algorithm. The detection algorithm was evaluated on a simulated data to detect a specific dynamic and on a clinical dataset of electrocardiogram signals collected from preterm infants for early detection of apnea bradycardia episodes. For simulated data, the...
Kinetics of Adsorption of DBT Sulfur Containing Compound of Gasoline via Nanostructured Adsorbent
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
Based on the new standards, less than 10 ppm sulfur is allowed for the automotive fuels. This has led researchers to try improving the present conventional methods as well as seeking alternative routes for refinement of the petroleum products so much to comply with the requirements. Since thiophenic fragments such as dibenzothiophene (DBT) are the most durable sulfur compounds in the current hydrodisulfurization method, many studies have been conducted over recent years on how to remove these compounds. In this thesis, the desulfurization of dibenzothiophene from gasoline via adsorption method was studied. In order to carry out the adsorption process, a nanocomposite of graphitic-carbon...
Translation and validation study of the Persian version of the Arthritis Impact Measurement Scales 2 (AIMS2) in patients with osteoarthritis of the knee
, Article BMC Musculoskeletal Disorders ; Volume 10, Issue 1 , 2009 ; 14712474 (ISSN) ; Parnianpour, M ; Askary Ashtiani, A. R ; Hadian, M. R ; Rostamian, A ; Montazeri, A ; Sharif University of Technology
2009
Abstract
Background. The Arthritis Impact Measurement Scales 2 (AIMS2) has not been translated and validated for Persian-speaking patients with osteoarthritis of the knee. This was to provide a validated instrument to measure functional disability and health-related quality of life in patients with osteoarthritis of the knee in Iran. The aim of this study was to culturally adapt and validate the AIMS2 for Persian-speaking patients with osteoarthritis of the knee in Iran. Methods. A consecutive sample of patients with knee osteoarthritis were asked to complete the AIMS2, the Short Form Health Survey (SF-36) and four visual analog scales for pain, joint stiffness, patient's and physician's global...
Experimental investigation of the stability of the floating water bridge
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 88, Issue 3 , 2013 ; 15393755 (ISSN) ; Azizpour Lindi, S ; Amjadi, A ; Jafari, N ; Irajizad, P ; Sharif University of Technology
2013
Abstract
When a high voltage is applied between two beakers filled with deionized water, a floating bridge of water is formed in between exceeding the length of 2 cm when the beakers are pulled apart. Currently two theories regarding the stability of the floating water bridge exist, one suggesting that the tension caused by electric field in the dielectric medium is holding the bridge and the other suggesting surface tension to be responsible for the vertical equilibrium. We construct experiments in which the electric field and the geometry of the bridge are measured and compared with predictions of theories of the floating water bridge stability. We use a numerical simulation for estimation of the...
Detection of Apnea Bradycardia from ECG Signals of Preterm Infants Using Layered Hidden Markov Model
, Article Annals of Biomedical Engineering ; Volume 49, Issue 9 , 2021 , Pages 2159-2169 ; 00906964 (ISSN) ; Shamsollahi, M. B ; Fatemizadeh, E ; Beuchée, A ; Hernández, A. I ; Montazeri Ghahjaverestan, N ; Sharif University of Technology
Springer
2021
Abstract
Apnea-bradycardia (AB) is a common complication in prematurely born infants, which is associated with reduced survival and neurodevelopmental outcomes. Thus, early detection or predication of AB episodes is critical for initiating preventive interventions. To develop automatic real-time operating systems for early detection of AB, recent advances in signal processing can be employed. Hidden Markov Models (HMM) are probabilistic models with the ability of learning different dynamics of the real time-series such as clinical recordings. In this study, a hierarchy of HMMs named as layered HMM was presented to detect AB episodes from pre-processed single-channel Electrocardiography (ECG). For...
The Effect of Different SLS Parameters on the Density of Polymer-Metal Parts
, M.Sc. Thesis Sharif University of Technology ; Movahhedi, Mohammad Reza (Supervisor)
Abstract
Selective Laser Sintering (SLS) is one of the powder-based Additive Manufacturing (AM) technology in which parts built by CO2 laser. In this research work, Titanium-PMMA-Stearic Acid powders are mixed together to produce parts by Indirect Metal Laser Sintering (IMLS) method. The optimum process parameters such as energy density, Percentage composition of Titanium-PMMA and Scan Sintering are obtained by adopting the Taguchi method for getting the maximum density and minimum porosity. Experiments are planned by Taguchi’s Mix-L8 orthogonal array. According to the results obtained from this study, the percentage of combination Ti-PMMA and Energy density, respectively, are a major parameters that...
Kinetics of sulfur removal from tehran vehicular gasoline by g-C3N4/SnO2 nanocomposite
, Article ACS Omega ; Volume 4, Issue 8 , 2019 , Pages 13180-13188 ; 24701343 (ISSN) ; Sadrnezhaad, S. K ; Sharif University of Technology
American Chemical Society
2019
Abstract
The graphitic carbon nitride/tin oxide (g-C3N4/SnO2) nanocomposite synthesized under microwave irradiation was used for adsorptive removal of sulfur-containing dibenzothiophene (DBT) from Tehran vehicular gasoline. High-resolution transmission electron microscopy, X-ray powder diffraction, energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller, Fourier-transform infrared spectroscopy, and field emission scanning electron microscopy techniques determined the adsorbent characteristics, and gas chromatography with a flame ionization detector determined the DBT concentration of the samples. Application of the experimental data into the solid/fluid kinetic models indicated a chemisorption...