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ghasempour--hamid
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Hybrid multiwalled carbon nanotubes and trioxide tungsten nanoparticles for hydrogen gas sensing
, Article Journal of Physics D: Applied Physics ; Volume 42, Issue 16 , 2009 ; 00223727 (ISSN) ; Iraji zad, A ; Sharif University of Technology
2009
Abstract
The WO3/multiwalled carbon nanotubes (MWNTs) hybrid films were fabricated by spin-coating on an alumina substrate. The structure, morphology, chemical composition and quality of the as-prepared WO3 nanoparticles, functionalized MWNTs and WO3/MWNTs hybrid films were studied by SEM, TEM, XRD, XPS, DLS and Raman spectroscopy methods. Results show that WO3 nanoparticles were nucleated on oxygenated functionalized MWNTs in hybrid suspension. After coating and annealing the films at 350 °C, the hybrid WO3/MWNTs films present rather linear gas sensitivity as a function of hydrogen concentrations at 300 °C. Results are discussed based on surface increase as well as development of two types of...
Agile web development methodologies: a survey and evaluation
, Article Studies in Computational Intelligence ; Volume 722 , 2018 , Pages 1-25 ; 1860949X (ISSN) ; Ramsin, R ; Sharif University of Technology
Springer Verlag
2018
Abstract
Dynamic and accessible web systems have gained utmost importance in modern life. Due to the competitive nature of such systems, they need to be superior as to performance, scalability, and security. Web systems typically require short time-to-markets, and it should be possible to easily implement new requirements into working web systems. These ideals have made agile methods especially suitable for developing such systems, as they promote productivity, facilitate continuous interaction with customers, and enhance the flexibility and quality of the software produced. When starting a web development project, selecting the methodology that fits the project situation can be an important factor...
Safe Personalized Treatment Recommendation System for Multimorbidity
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
Multimorbidity in an individual is a typical and increasing condition and a major challenge in healthcare. The goal of treatment recommendation for such patients is to decide the most effective combination of treatments. Doctors typically prescribe medication based on their intuition and experience. However, due to knowledge gaps or unintended biases, often times these clinical decisions can be sub-optimal. Broad adoption and usage of electronic health records (EHRs) in the last decade has opened up a great opportunity to leverage healthcare data to improve clinical decisions.In this approach we use EHR and drug-drug interaction (DDI) information to prescribe medications. We use multiple...
Approximation Approaches for Ontology Alignment
, M.Sc. Thesis Sharif University of Technology ; Abolhassani, Hassan (Supervisor)
Abstract
Ontology alignment is a process for selection of a good mapping between entities of two (or more) ontologies. It can be viewed as a two phase process of: 1) Find the similarity of each pair of entities from two ontologies, and 2) Extraction of an optimal or near optimal mapping. Many researches had been down in the first phase, but researches in the second phase are little. Mapping extraction approaches applied in ontology alignment use similarity matrix to extract mapping, and ontologies have not any role in mapping extraction phase. One of the most important components in ontology is its structure which can help us in alignment extraction.
In this thesis, an approach was proposed that...
In this thesis, an approach was proposed that...
Evaluation the Surface Settlement and Interaction Between Tunnelinline2 and Metro Station Inline1 of Mashhad Metro at Intersection Using 3-D Numerical Modeling
, M.Sc. Thesis Sharif University of Technology ; Sadaghiani, Mohammad Hossein (Supervisor)
Abstract
In this study, the interaction of tunneling of line 2 of Mashhad metro and existing metro station (Shariati station) in line 1 has been investigated. To produce the stress and displacement which is caused by excavation of station, the process of station excavation has been modeled by method of cut and cover.This method is the common method for station construction at Shallow depth and is used in several cases in line 1 of Mashhad metro. The piled-raft system is used in foundation of central part of the station to reduce the settlements and the effects of interactions between the station and new tunnel. The new tunnel under the station is surrounded by two rows of lateral piles with distance...
Stochastic Cauchy Problem in UMD Banach Spaces
, M.Sc. Thesis Sharif University of Technology ; Zohuri Zangeneh, Bijan (Supervisor)
Abstract
We discuss, in the setting of UMD Banach spaces E, existence, uniqueness and the continuous dependence on the data A, F, G and of mild solutions of semilinear stochastic evolution equations with multiplicative noise of the form dX(t) = [AX(t) + F(t;X(t))]dt + G(t;X(t))dWH(t); t 2 [0; T]; X(0) = ; Where A generates an analytic C0-semigroup on a UMD Banach space E and WH is a cylindrical Brownian motion with values in a Hilbert space H. We can see that if the mappings F : [0; T] E ! E and G : [0; T] E ! L(H;E) satisfy suitable Lipschitz conditions and is F0-measurable and bounded, then this problem has a unique mild solution.And We arw going to review continuous dependence of the solutions...
Csr Effect on Customer Loyalty during a Pandemic: a Case Study of Mobile-Phone Operator Companies in Iran
, M.Sc. Thesis Sharif University of Technology ; Kiamehr, Mehdi (Supervisor)
Abstract
Customer loyalty plays one of the most vital roles in business profitability. This concept gives special prominence to attaining new customers, which is by far less costly than attracting new ones. Therefore, investigating the impact of factors affecting customer retention is of precise significance. In the respect, corporate social responsibility, as an imperative factor impacting customer loyalty, gained more attention by various companies in the last decades.Over the past few months, the world has encountered the hazard of the Coronavirus pandemic. Most aspects of daily life in different parts of the globe have been affected by this disease. Companies are no exception. The coronavirus has...
Investigating the Effect of Communication of the Family Nature of Business on the Organizational Reputation, Measuring the Mediating Role of Brand Equity and Corporate Social Responsibility
, M.Sc. Thesis Sharif University of Technology ; Khalili Nasr, Arash (Supervisor)
Abstract
According to official statistics, family businesses form the majority of businesses around the world. When we talk about businesses, we are more likely to say that those firms face issues related to family businesses.One of the trending topics that has recently been considered by researchers and a lot of research has been done in this regard, is specific issues related to marketing and branding of family businesses.In this study, we tried to examine the family business brand in terms of reputation. Reputation is the perception in the minds of brand stakeholders about the brand and the organization. So we tried to take as fair and accurate a sample as possible, to seek the opinions of...
The moment method for fiber raman amplifier gain ripple minimization
, Article Optics Communications ; Volume 281, Issue 14 , 2008 , Pages 3673-3680 ; 00304018 (ISSN) ; Farman, F ; Ghasempour, A ; Sharif University of Technology
2008
Abstract
We aim to propose a novel fiber Raman amplifier modeling based on the moment method, which is previously introduced for modeling the inhomogeneous Erbium doped fiber amplifiers and recently employed to analyze the fiber Raman amplifier with continuous pump spectrum. In this model, the number of governing equations is independent of the number of signals and according to the degree of accuracy it is proportional to the number of pumps. This method is employed to analyze the Raman fiber amplifiers with an arbitrary input signal line shape and to minimize the gain ripple of the fiber Raman amplifier with respect to the pump powers and pump frequencies. © 2008 Elsevier B.V. All rights reserved
Visible light photoinactivation of bacteria by tungsten oxide nanostructures formed on a tungsten foil
, Article Applied Surface Science ; Volume 338 , May , 2015 , Pages 55-60 ; 01694332 (ISSN) ; Azimirad, R ; Amini, A ; Akhavan, O ; Sharif University of Technology
Elsevier
2015
Abstract
Antibacterial activity of tungsten oxide nanorods/microrods were studied against Escherichia coli bacteria under visible light irradiation and in dark. A two-step annealing process at temperatures up to 390 °C and 400-800 °C was applied to synthesize the tungsten oxide nanorods/microrods on tungsten foils using KOH as a catalyst. Annealing the foils at 400 °C in the presence of catalyst resulted in formation of tungsten oxide nanorods (with diameters of 50-90 nm and crystalline phase of WO3) on surface of tungsten foils. By increasing the annealing temperature up to 800 °C, tungsten oxide microrods with K2W6O19 crystalline phase were formed on the foils. The WO3 nanorods showed a strong...
In pursuit of a replacement for conventional high-density polyethylene tubes in ground source heat pumps from their composites – a comparative study
, Article Geothermics ; Volume 87 , September , 2020 ; Fatehifar, M ; Ghasempour, R ; Noorollahi, Y ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Ground-source heat pumps, as the most environmentally friendly and energy-efficient air conditioning technology, suffer from a great required length of ground heat exchanger, partly arising from the low thermal conductivity of high-density polyethylene tubes commonly used in ground heat exchangers. In an attempt to find a replacement with an acceptable thermal conductivity for high-density polyethylene tubes, in this study, first, a comprehensive comparative study on fillers commonly used in thermally conductive polymer composites and resulting high-density polyethylene composites was conducted. Then, based on the advantages and disadvantages presented, an appropriate composite was selected...
Tuning of random lasers by means of external magnetic fields based on the Voigt effect
, Article Optics and Laser Technology ; Volume 47 , April , 2013 , Pages 121-126 ; 00303992 (ISSN) ; Mahdavi, S. M ; Bahrampour, A. R ; Sharif University of Technology
2013
Abstract
It has been proposed that emission spectrum of random lasers with magnetically active semiconductor constituents can be made tunable by external magnetic fields. By employing the FDTD method, the spectral intensity and spatial distribution of electric field are calculated in the presence of an external magnetic field. It is numerically shown that due to the magneto-optical Voigt effect, the emission spectrum of a semiconductor-based random laser can be made tunable by adjusting the external magnetic field. The effect of magnetic field on the localization length of the laser modes is investigated. It is also shown that the spatial distribution of electric field exhibited remarkable...
Numerical Investigation of Combustion of Cryogenic H2-O2 Propellant under Sub-Critical Condition
, M.Sc. Thesis Sharif University of Technology ; Mardani, Amir (Supervisor) ; Farshchi, Mohammad (Supervisor)
Abstract
The present work is concerned with numerical simulation of spray flame for rocket combustor (MASCOTTE A-10 test case at 10 bar pressure) based on cryogen gaseous hydrogen and liquid oxygen at specific condition. This liquid oxygen and gaseous hydrogen single element combustor experiment has been the focus of many numerical studies which is representative of combustion in rocket combustion chamber condition. The purposed strategy relies on hybrid Eulerian-Lagrangian framework that continuous phase is evaluated by Reynolds average Navier-stokes (RANS) equation with quick discretization method and dispersed phase of combustion chamber atmosphere is evaluated by discrete phase method (DPM). To...
Design and fabrication of sensitive carbon nanotubes/PMMA film for acetone vapour detection
, Article International Journal of Nanomanufacturing ; Volume 5, Issue 3-4 , 2010 , Pages 268-277 ; 17469392 (ISSN) ; Iraji Zad, A ; Hormozi Nezhad, M. R ; Sharif University of Technology
2010
Abstract
We present gas sensing property of carbon nanotubes (CNTs) polymethylmethacrylate (PMMA) composite as the active element for acetone vapour detection at room temperature. The polymeric films were formed by spin coating method on SiO2 substrates. Then they were activated by dropping the CNTs suspension in acetone on the PMMA films. The CNT/PMMA films were characterised by SEM, TEM and Raman spectroscopy. Variation of film's electrical resistance after exposure polar and non-polar gases is utilised as the principle of gas sensing. The experimental results showed that the samples present chemical selectivity and reversibility toward polar gases especially acetone vapour
Pd doped WO3 films prepared by sol-gel process for hydrogen sensing
, Article International Journal of Hydrogen Energy ; Volume 35, Issue 2 , 2010 , Pages 854-860 ; 03603199 (ISSN) ; Iraji zad, A ; Rahimi, F ; Ghasempour, R ; Sharif University of Technology
2010
Abstract
The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA). Palladium chloride salt was dissolved in the sol with different Pd:W molar ratios and coated on Al2O3 substrates by spin coating method. XRD and XPS techniques were used to analyze the crystal structure and chemical composition of the films before and after heat treatment at 500 °C. We observed that Pd can modify the growth kinetic of tungsten trioxide nanoparticles by reducing the crystallite size and as a result can improve hydrogen sensitivity. Resistance-sensing measurements indicated sensitivity of about 2.5 × 104 at room temperature in hydrogen concentration of 0.1% in air. Considering all sensing parameters,...
Numerical simulation of a concentrating photovoltaic-thermal solar system combined with thermoelectric modules by coupling Finite Volume and Monte Carlo Ray-Tracing methods
, Article Energy Conversion and Management ; Volume 172 , 2018 , Pages 343-356 ; 01968904 (ISSN) ; Narei, H ; Ghasempour, R ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
During the last decades, the adoption of more strict safety and environmental regulations, as well as a rise in energy costs, sparked an increasing interest in the design of renewable energies systems, particularly solar systems, to supply both electrical power and heat. Because of their capability to simultaneously supply both electricity and heat, concentrating photovoltaic-thermal and thermoelectric hybrid systems have recently attracted scholarly attention. In this study, a detailed three-dimensional computational model of a novel concentrating photovoltaic-thermal solar system combined with thermoelectric modules in an integrated design with a triangular absorber and corresponding...
The effect of the Cr and Mo on the physical properties of electrodeposited Ni-Fe alloy films
, Article Journal of Alloys and Compounds ; Volume 386, Issue 1-2 , 2005 , Pages 43-46 ; 09258388 (ISSN) ; Iraji zad, A ; Dolati, A ; Ghasempour, R ; Sharif University of Technology
2005
Abstract
Ni-Fe and the Ni-Fe-Cr-Mo alloy films were electrodeposited from a chloride solution containing complexing compounds on ITO/glass substrates. AFM studies revealed a spherical structure for the alloy films with roughnesses from 10 up to 50 nm. The Ni-Fe-Cr-Mo alloy films were found to have a fine-grain structure. The quaternary alloy compounds containing up to 4% Cr and 2% Mo showed higher resistivity and little decrease in magnetoresistance (MR) relative to the Ni80Fe20 alloy compound. The MR of the quaternary alloy compounds was decreased for higher Cr and Mo contents. Moreover, the anisotropy (AMR) was also decreased by the addition of Cr and Mo to Permalloy films. Auger studies indicated...
Hydrogen sensing properties of multi-walled carbon nanotube films sputtered by Pd
, Article International Journal of Hydrogen Energy ; Volume 35, Issue 9 , 2010 , Pages 4445-4449 ; 03603199 (ISSN) ; Mortazavi, S. Z ; Iraji zad, A ; Rahimi, F ; Sharif University of Technology
2010
Abstract
Multi-Walled Carbon nanotube (MWCNTs) films were obtained by Thermal Chemical Vapor Deposition method and coated by palladium sputtering process. Raman spectroscopy was used to study alteration in quality of the carbon nanotubes after the sputtering process. Fourier Transform Infra Red (FTIR) spectroscopy showed that hydrogenation process can reduce the C{double bond, long}O to C-O and also produce O-H bond. Furthermore, the electrical resistance measurement for Pd/MWNTs films was performed in a chamber with 1% hydrogen gas in a constant dry air flow. Hydrogen sensing behavior of the films was investigated at 50 °C. Pd/MWCNTs films presented an irreversible gas response to hydrogen in the...
A review of thermal conductivity of various nanofluids
, Article Journal of Molecular Liquids ; Volume 265 , 2018 , Pages 181-188 ; 01677322 (ISSN) ; Mirlohi, A ; Alhuyi Nazari, M ; Ghasempour, R ; Sharif University of Technology
2018
Abstract
In the present paper, several experimental and theoretical studies conducted on the thermal conductivity of nanofluids are represented and investigated. Based on the reviewed studies, various factors affect thermal conductivity of nanofluids such as temperature, the shape of nanoparticles, concentration and etc. Results indicated the increase in temperature and concentration of nanoparticles usually leads to the higher thermal conductivity of nanofluids. In addition, it is concluded that there are some novel approaches in order to obtain nanofluids with more appropriate thermal properties including using binary fluids as the base fluid or utilizing hybrid nanofluids. © 2018 Elsevier B.V
Tunability of terahertz random lasers with temperature based on superconducting materials
, Article Journal of Applied Physics ; Volume 112, Issue 4 , 2012 ; 00218979 (ISSN) ; Bahrampour, A. R ; Mahdavi, S. M ; Hosseini, M ; Sharif University of Technology
2012
Abstract
We theoretically demonstrate the tunabiltiy of terahertz random lasers composed of high temperature superconductor YBCO and ruby layers as active medium. The considered system is a one-dimensional disordered medium made of ruby grain and YBCO. Finite-difference time domain method is used to calculate the emission spectrum and spatial distribution of electric field at different temperatures. Our numerical results reveal that the superconductor based random lasers exhibit large temperature tunability in the terahertz domain. The emission spectrum is significantly temperature dependent, the number of lasing modes and their intensities increase with decreasing temperature. Also, we make some...