Loading...
Search for:
moosavi--saba
0.119 seconds
Total 173 records
Wideband and narrowband circuit models for fano-shape guided-mode resonance
, Article IEEE Journal of Quantum Electronics ; Volume 55, Issue 3 , 2019 ; 00189197 (ISSN) ; Memarian, M ; Mehrany, K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we propose two different types of circuit models for Fano-shape guided-mode resonance (GMR) in waveguide gratings. Both the models constitute a resonant tank circuit together with a direct non-resonant channel between the incident and scattered light. One neglects the frequency dependence of the direct non-resonant channel and is only more accurate in the immediate vicinity of the Fano-type resonance. The other accounts for the frequency dependence of the direct non-resonant channel and thus remains accurate within a wider range of frequencies. The former being referred to as the narrow-band model is extremely accurate, insofar as the isolated GMR is of interest within a...
Wide-and narrow-band circuit models for fano-shape guided mode resonance
, Article IEEE Journal of Quantum Electronics ; 2019 ; 00189197 (ISSN) ; Memarian, M ; Mehrany, K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we propose two different types of circuit models for Fano-shape guided mode resonance (GMR) in waveguide gratings. Both models constitute a resonant tank circuit together with a direct non-resonant channel between the incident and the scattered light. One neglects the frequency dependence of the direct non-resonant channel and is only more accurate in the immediate vicinity of the Fano type resonance. The other accounts for the frequency dependence of the direct non-resonant channel and thus remains accurate within a wider range of frequencies. The former being referred to as the narrow-band model is extremely accurate insofar as the isolated GMR is of interest within a narrow...
Wide-and narrow-band circuit models for fano-shape guided mode resonance
, Article IEEE Journal of Quantum Electronics ; 2019 ; 00189197 (ISSN) ; Memarian, M ; Mehrany, K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we propose two different types of circuit models for Fano-shape guided mode resonance (GMR) in waveguide gratings. Both models constitute a resonant tank circuit together with a direct non-resonant channel between the incident and the scattered light. One neglects the frequency dependence of the direct non-resonant channel and is only more accurate in the immediate vicinity of the Fano type resonance. The other accounts for the frequency dependence of the direct non-resonant channel and thus remains accurate within a wider range of frequencies. The former being referred to as the narrow-band model is extremely accurate insofar as the isolated GMR is of interest within a narrow...
Range-free passive acoustic localization
, Article 2008 International Conference on Intelligent Sensors, Sensor Networks and Information Processing, ISSNIP 2008, Sydney, NSW, 15 December 2008 through 18 December 2008 ; 2008 , Pages 37-42 ; 9781424429578 (ISBN) ; Abolhassani, H ; Ghodsi, M ; Sharif University of Technology
2008
Abstract
We propose a range-free localization framework in which a network of randomly deployed acoustic sensors can passively use natural acoustic phenomena within its environment to localize itself. We introduce a novel approach for registration of sensors observations which takes advantage of a clustering technique on triplets of associated observations. A Bayesian filtering method is employed to incrementally improve system state estimation as more observations become available. To the best of our knowledge this is the first work done on range-free passive acoustic localization. Simulation experiments of the proposed algorithms are presented. © 2008 IEEE
Automatic Acoustic Localization in Sensor Networks Using Environmental Natural Acoustic Phenomena
, M.Sc. Thesis Sharif University of Technology ; Abolhassani, Hassan (Supervisor)
Abstract
We propose a range-free localization framework in which a network of randomly deployed acoustic sensors can passively use natural acoustic phenomena within its environment to localize itself. We introduce a novel approach for registration of sensors observations which takes advantage of a clustering technique on triplets of associated observations. A Bayesian filtering method is employed to incrementally improve system state estimation as more observations become available. To the best of our knowledge this is the first work done on range-free passive acoustic localization. Furthermore, we have proposed a simple but effective and efficient acoustic detection method which can be used to...
Two-dimensional edge detection by guided mode resonant metasurface
, Article IEEE Photonics Technology Letters ; Volume 30, Issue 9 , 1 May , 2018 , Pages 853-856 ; 10411135 (ISSN) ; Tavakol, M. R ; Karimi Khoozani, P ; Khavasi, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In this letter, a new approach to perform edge detection is presented using an all-dielectric complimentary metal-oxide-semiconductor-compatible metasurface. Our design is based on the guided-mode resonance, which provides a high quality factor resonance to make the edge detection experimentally realizable. The proposed structure is easy to fabricate, and it can be exploited for detection of edges in two dimensions due to its symmetry. In addition, a tradeoff between gain and the resolution of edge detection is discussed, which can be adjusted using appropriate design parameters. The proposed edge detector potentially can be used in ultrafast analog computing and image processing. ©...
Coarsening dynamics of dewetting nanodroplets on chemically patterned substrates
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 86, Issue 1 , July , 2012 ; 15393755 (ISSN) ; Sharif University of Technology
2012
Abstract
Mesoscopic hydrodynamic equations are solved to investigate coarsening dynamics of two interacting nanodroplets on chemically patterned substrates. The effects of different parameters such as the surface chemical pattern, the slip length, the profile of the disjoining pressure, the size of the droplets, and the contact angles on the coarsening are studied. Our results reveal that the presence of a chemical heterogeneity can enhance or weaken the coarsening dynamics depending on the pattern type and positions of the droplets on the substrate. Also increasing the contact angles to values larger than a critical value may qualitatively change the coarsening process, and the profile of the...
Study, Analysis & Optimizing The Process Of Approval, Design & Implementation Of Projects In The Iranian Oil Terminal Company(IOTC)
, M.Sc. Thesis Sharif University of Technology ; Mostafavi, Mostafa (Supervisor)
Abstract
Since the Iranian oil terminals company(I.O.T.C.) has been the main and strategic gateway of exporting petroleum in the country and plays an important role in the optimum continuity of national, regional and international energy supply chain and also conducting the needed projects whit a desirable quality and minimum time and cost has a prominent influence on steady continuity of manufacturing, importing and exporting of petroleum and gas production. The main purpose of doing this thesis is diagnosing the process of approval, design and implementation of projects in the I.O.T.C., Thus, whit regarding to the modern needs of implementing projects and the necessity of reviewing the structure...
Numerical Investigation of Motion of Droplets in Micro and Nanochannels
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
In this research, droplet motion in symmetric and asymmetric junctions in micro and nano scales was investigated. Droplets motion in symmetric and asymmetric junctions have many applications in many industries such as chemical and pharmacy. In this research symmetric T-junction in micro and nano sizes was simulated numerically in 2D and 3D formes. Also asymmetric T-junction (with unequal width branches) was simulated numerically in two cases, 2D and 3D. In the asymmetric T-junction, also an analyrical theory was developed. Numerical simulation was performed by using VOF techniqe and analytical theory was developed by thin film theory. For verifying the accuracy of numerical solution, grid...
Analytical and Numerical Study of Dynamics of Wettability Driven Droplets in Smooth And Corrugated Channels
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
We studied dynamics of droplets inside channels under surface forces created by chemicalsteps on the channel walls. A multi-component Shan-Chen lattice Boltzmann method isused for this purpose.The effects of parameters such as the channel height, viscosity anddensity ratios on the results were investigated for homogeneous and grooved substrates. Alsoan analytical solution was developed for droplets under chemical heterogeneities in channels with smooth surfaces. The solution considers a general condition, namely, asymmetry of the contact angles on the top and bottom walls, the viscosity of the gas as the second fluid and the effect of the channel height. Then using Shan-Chen lattice...
Coarsening Dynamics of Nanodroplets
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Hydrodynamic mesoscopic equations are solved using boundary integral method to investigate the coarsening dynamics of two dimensional nanodroplets. The dynamics is probed by locating two drops on homogeneous, chemical heterogeneous and physical heterogeneous substrates respectively. For homogeneous substrate, the effect of different parameters like droplets distance, slip boundary condition, surface contact angle and disjoining pressure type on the dynamics is studied. Results reveal that increasing the contact angles to values larger than a critical value may qualitatively change the coarsening process and the profile of the disjoining pressure can appreciably modify the coarsening rate....
Numerical Investigation of Motion of Nanodroplets on Wetting Gradient Surfaces
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
A droplet placed on the boundary of two solids with different wettabilities will move to the more wettable part. This is a well-known phenomenon and has been extensively used in a variety of processes and applications ranging from biological systems and ink jet printing to the commercial lab-on-a-chip. Because of its importance, many studies are conducted around this phenomenon. The difference between the equilibrium contact angles of the droplet on the two parts gives rise to an interfacial driving force which moves the droplet. Such a motion is not continuous as the droplet slides to the more wettable area, the driving force diminishes and consequently the droplet stops. A non-stop motion...
Three Dimensional Simulation of Morphology of Nanodroplets Near and on Structured Substrates
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Mesoscopic hydrodynamic equations are solved employing a VOF based method to investigate the equilibrium shape of nanodroplets positioned over various topographic geometries of the supporting substrate for three-dimensional systems. By taking into account liquid-liquid and liquid-solid interactions a complex distribution for inter-molecular forces over the substrates (the disjoining pressure) is observed. In this research we show that motion of nanodroplets not only caused by contact angle difference in drplets two sides, but also depend on disjoining pressure parameters.Geometries with increasing complexities, from wedges to three dimensional edges and wedges, were explored with the main...
Numerical Investigation of Instabilities of Flow in Micro-fluid
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
This research concerns investigating the behavior of two-phase flow in the inlet and outlet of the microchannels.Both the droplet based and the continuous microfluidics are considered. For the continuous system whenthe minor fluid enters the microchannel, due to ratio of viscosity of two fluids, viscous folding occurs.Viscous folding phenomena is similar to the buckling phenomena in solids.This means that the viscosity of the fluid, which is applied to two sides of the fluid layer, causes folding the fluid layer and changing the shape of it. For the study we employ a VOF based numerical routine. In order to verify numerical results, the grid and the time step independenciesare checked. In...
Experimental and Theoritical Study of Thermo-acoustic Effect in Carbon Nanotubes
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Carbon Nanotube webs exhibit interesting properties when used as thermo-acoustic projectors. This work studies thermo-acoustic phenomena of these sound sources both in near and far field regions. Our three-dimensional simulation and experimental data show pressure waves are highly affected by dimensions of sound sources in near field due to interference effects. Although pressure amplitude increases with increasing frequencies, maximum pressure amplitude reached in lower frequencies may become larger than its maximum amount at higher frequencies because of interference effects. Measurement of different surface area sources shows generation of sound waves in far field is independent of...
Simulation of Drag Reduction Via Microgrooves
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Drag reduction on surfaces always has been a great case of study, especially in transport industry. This project discusses the external laminar flow of a single-phase fluid over a flat plate and the effects of making rectangular tiny grooves - in micron or millimeter - on them to reduce total drag. Making grooves with appropriate geometry on surfaces causes the fluid-solid contact area on the groove's surface turn into fluid-fluid and as a result the fluid will not shed into the groove. In other words the flow instead of having a no-slip boundary condition on inner surfaces of the groove, creates vortices in them that causes a remarkable reduction in velocity gradient followed by a skin...
Effect of Surface Structure on Drag Reduction
,
M.Sc. Thesis
Sharif University of Technology
;
Moosavi, Ali
(Supervisor)
Abstract
This project studies the effects of different blade and different velocity fields on reducing drag coefficient. A numerical simulation was set up for a circular cylinder to represent the effects of blade on reducing drag. In this study, velocity, density and the cylinder diameter were constant and different viscosities were selected for different regime flows. The computational fluid dynamic programmer FLUENT was used to simulate results for this project. Arrays of cylinders were set up to see the changes in velocity profiles and drag coefficients for a range of Re. In this study, I studied three cases of setting up blade and concentrated on friction drag coefficient and pressure drag...
Numerical Analysis of Underwater and Within Air Sound Generation by using Carbon Nanotube
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Carbon nanotubes have special thermodynamic properties which makes suitable as a thermo-acoustic sound source. Recently it is shown that by using these nanotubes it is possible to generate strog sound waves in air or water. Experimental analysis of phenomenon can be complicated and expensive. Hence this fact, in this study using molecular dynamic simulation, numerical analysis of sound generation with CNTs in air and water is discussed. For this purpose, the required structue of the system is generated and it has reaced equilibrium. This process has been done for 6 different CNT and for each CNT there are 5 different distances between them. Althogether, 30 different cases has is used for...
Numerical Investigation of Nano-Particles Dispersion and Deposition in Crossing of Elliptical Obstacles Networkusing Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Investigation of transport and deposition of aerosol particles has been of interest to researchers in many branches of science. Various numerical and experimental methods has been utilized in particulate fluid flows studies. In recent relevant researches lattice Boltzmann method has been widely used and is reported to be a robust and efficient method. In present study, numerical investigation of dispersion and deposition of aerosol particles is studies in the channel, containing elliptical obstacles geometry using Lattice Boltzmann Method. Fluid flow simulations are performed using LBM while for the study of particle transport and deposition, tracking and the motion equations of them,...
Molecular Dynamic Simulation of Water Desalination Across Porous Single Layer Graphene Membrane
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
In recent years carbon nanotubes and other carbon nanostructures such as graphene sheets have attracted a lot of attention due to their unique mechanical, thermal and electrical properties. These structures can be used in desalination of sea water, removal of hazardous substances from water tanks, gases separation, and so on. The nano porous single layer graphene membranes are very efficient for desalinating water due to their very low thickness. In this study, the mechanism of passing water and salt ions through nano porous single-layer graphene membrane are simulated using classical molecular dynamics. In the simulation, in order to separate salt ions from the water, the effects of applied...