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farrokhi-rad--morteza
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Electrophoretic deposition of titania nanoparticles in different alcohols: Kinetics of deposition
, Article Journal of the American Ceramic Society ; Volume 94, Issue 8 , 2011 , Pages 2354-2361 ; 00027820 (ISSN) ; Ghorbani, M ; Sharif University of Technology
2011
Abstract
The suspension of titania nanoparticles in different alcohols (methanol, ethanol, and butanol) was prepared and triethanolamine (TEA) was used as a dispersant. The suspensions were characterized by different tests such as sedimentation, zeta potential, and Fourier transform infrared spectroscopy. The electrophoretic deposition (EPD) was performed at various voltages and times. EPD from butanolic suspension (0.8 g/L TEA) showed the slowest kinetics, because of the low electrophoretic mobility of titania nanoparticles in it (2.40 × 10-5 cm2·(V·s)-1). Also, it was observed that at low voltages (5, 10, and 20 V), the EPD kinetics from methanolic suspension (0 g/L TEA) was the fastest; however,...
Stability of titania nano-particles in different alcohols
, Article Ceramics International ; Volume 38, Issue 5 , 2012 , Pages 3893-3900 ; 02728842 (ISSN) ; Ghorbani, M ; Sharif University of Technology
2012
Abstract
The alcoholic suspensions of titania nano-particles were prepared using the methanol, ethanol, isopropanol and butanol as the solvents as well as triethanolamine (TEA) as an dispersant. The colloidal stability of suspensions, both in the absence as well as presence of TEA, was studied by measuring the zeta potential, sedimentation, pH and electrical conductivity of suspensions, dispersant adsorption and particles size distribution. Results showed that in the absence of TEA, the stability of the suspensions increases with the molecular size of alcohol (from methanol to butanol), while the zeta potential decreases. It was also observed that with the addition of TEA up to the optimum dosage (4...
The Effect of Solvent Type on the Characteristic of TiO2 Nanometric Coatings Produced by Electrophoretic Method
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Titania is semiconductor material and have many applications including photocatalysis, photochromic, air and water purification, sensors, and solar cell. In electrophoretic deposition, charged particles dispersed in a stable suspension move towards an oppositely charged electrode, and form dense layer of deposit on it. In this investigation electrophoretic deposition of titania nano-particles in suspensions prepared by different solvents (methanol, ethanol and butanol) with and without dispersant (triethanolamine and polyethylenimine), was studied. Well stabilized suspensions, prepared for electrophoretic deposition. The effects of solvent type, additive concentration, mechanism of particles...
Thermal Behavior of Rechargeable Li-ion Batteries; Experimental Evaluations and Modeling
, Ph.D. Dissertation Sharif University of Technology ; Baghalha, Morteza (Supervisor) ; Kazemeini, Mohammad (Co-Advisor)
Abstract
The main objective of this research is to experimentally evaluate thermal behavior of commercially available rechargeable Li-ion batteries based on minimum measurements on main battery parameters and then develop experimental based models to investigate their thermal behavior. Li-ion batteries with Graphit anodes and Li(Ni0.8¬Co0.15Al0.05)O2 cathodes will be used for this purpose. Voltage and temperature developments during cycling under various currents at controlled ambient temperatures are measured by battery tester. Measurements show that temperature evolutions demonstrate falls and rises at specific State-of-Charge (SoC) of the battery during cycling and therefore some heat consumers...
Impact of Subsidies on Evolution of Fertility and Human Capital in the Iranian Economy
, M.Sc. Thesis Sharif University of Technology ; Nili, Farhad (Supervisor)
Abstract
On the contrary to common explanations of fertility transition in the Iraninan Economy there has been a growing human capital without decline of fertility for some decades followed by a rapid fall in fertility without a higher growth of human capital during the next decades. Accounting for these facts we propose a new link between subsidies financed by exogenous oil revenue and the evolution of fertility and human capital. While the educational subsidy accelerates the growth of human capital, the presence of financial subsidies keeps fertility from declining. Then, fertility declines with sizeable delay but sharply because (i) high fertility in first generations implies a growth rate of...
Predication of prosodic data in Persian text-to-speech systems using recurrent neural network
, Article Electronics Letters ; Volume 39, Issue 25 , 2003 , Pages 1868-1869 ; 00135194 (ISSN) ; Ghaemmaghami, S ; Sharif University of Technology
2003
Abstract
A simplified four-layer recurrent neural network (RNN) based architecture is introduced to generate prosodic information for improving naturalness in Persian text-to-speech (TTS) systems. The proposed RNN uses the first two layers at word level and the last two layers at syllable level to provide the TTS system with major prosodic parameters, including: pitch contour, energy contour, length of syllables, length and onset time of vowels, and duration of pauses. The experimental results show improvement of accuracy in prediction of prosodic parameters, as compared to similar prosody generation systems of higher complexity
Detection of streamflow trends and variability in karun river-Iran as parts of climate change and climate variability
, Article Proceedings of World Environmental and Water Resources Congress 2009 - World Environmental and Water Resources Congress 2009: Great Rivers, 17 May 2009 through 21 May 2009, Kansas City, MO ; Volume 342 , 2009 , Pages 4782-4793 ; 9780784410363 (ISBN) ; Abrishamchi, A ; Sharif University of Technology
2009
Abstract
This paper describes the application of statistical and spectral procedures that identifies trends and periodicity in streamflow time series. The results of Mann-Kendall and seasonal Kendall tests (non-parametric tests which are known as appropriate tools in detecting linear trends of hydrological time series) shows negative trends especially during low water months (August to November). This downward trend is more significant in October. But these methods can not interpret periodic behavior. Hence spectral procedures were applied on data series to investigate periodicities in streamflow data series. Fourier and Continuous Wavelet Transform (CWT) analyses produce evidence of interannual...
Theoretical modeling and simulation of higher order FWM crosstalks in multichannel WDM optical communication systems
, Article Advanced Materials Research, Xiamen ; Volume 660 , 2013 , Pages 130-134 ; 10226680 (ISSN) ; 9783037856413 (ISBN) ; Noshad, M ; Farrokhi, A ; Sharif University of Technology
2013
Abstract
In this paper, we derive a theoretical model for the higher order FWM power in WDM networks with NZDSF fibers for the first time. We have investigated the higher order FWM power theoretically and by numerical simulations. Dividing the fiber into finite number of elements and applying the boundary conditions, allow us derive an expression for second order power penalty. At the end of each element we derive the first order FWM power for all wavelengths and use these values to calculate the second order FWM power in the next element. Consequently, for each channel we can compute the total second order FWM power penalty at the end of the fiber
Inverse design of supersonic diffuser with flexible walls using a Genetic Algorithm
, Article Journal of Fluids and Structures ; Volume 22, Issue 4 , 2006 , Pages 529-540 ; 08899746 (ISSN) ; Ziaei-Rad, M ; Sharif University of Technology
2006
Abstract
An efficient algorithm for the design optimization of the compressible fluid flow problem through a flexible structure is presented. The methodology has three essential parts: first the behavior of compressible flow in a supersonic diffuser was studied numerically in quasi-one-dimensional form using a flux splitting method. Second, a fully coupled sequential iterative procedure was used to solve the steady state aeroelastic problem of a flexible wall diffuser. Finally, a robust Genetic Algorithm was implemented and used to calculate the optimum shape of the flexible wall diffuser for a prescribed pressure distribution. © 2006 Elsevier Ltd. All rights reserved
Determiniation of Optimal Interruptible Load Contracts in Smart Distribution Networks Considering Reliability Indices
, M.Sc. Thesis Sharif University of Technology ; Fotuhi Firouzabad, Mahmud (Supervisor)
Abstract
Nowadays, considering the dependence of the life quality to the electric energy, exhaustion of the existing facilities in the distribution networks, and restructuring of the electric industry, the reliability improvement turns out to be one of the most important considerations in order to reducing the operational cost. Furthermore, the expansion of existing networks, substitution, and refinement of the exhausted facilities for improving the reliability can lead to remarkable expenses. Considering the limitations of budgets of distribution network companies, these plans cannot be put into practice. Therefore, operators and planners of this industry have to find ways to operate the existing...
Optimal Design of Partial State-Feedback Controllers
, M.Sc. Thesis Sharif University of Technology ; Karimi, Houshang (Supervisor) ; Karimi, Masoud (Supervisor)
Abstract
Design of optimal controllers for nonlinear systems and even for linear systems is one of the most important parts of the control science. In optimal controller design, our aim is to maximize or minimize some kind of cost function associated with that particular problem. Such cost functions are usually combining the overall control effort, system’s energy, or some other important specifications of the system. Explicit solution for linear quadratic controllers exists under some mild conditions such as stabilizability of the system. The solution is in the form of a full state-feedback law. But in practical problems, we may not have access to all of the system state variables. The problem can...
Ant colony algorithm for the shortest loop design problem [electronic resource]
, Article Computers and Industrial Engineering, Elsevier ; Volume 50, Issue 4, August 2006, Pages 358–366 ; Kazemi, Morteza ; Sharif University of Technology
Abstract
In this paper, a new algorithm for solving the shortest loop design problem is presented. The shortest loop design problem is to find the shortest loop for an automated guided vehicle covering at least one edge of each department of a block layout. In this paper, first it is shown that this problem can be represented as a graph model. The properties of the presented model enable us to design a meta-heuristic based on ant colony system algorithm for solving the shortest loop design problem. Computational results show the efficiency of our algorithm in compare to the other techniques
Implementaion of 5S in Zarin Iran Porcelain Industries
, M.Sc. Thesis Sharif University of Technology ; Parida, Aditiya (Supervisor)
Abstract
This project shows the flow of implementing a 5s Program into a factory. From it’s first step by studying current situation until the last step implementing and monitoring the results. Manufacturing companies have a growing, market-driven need to adopt World Class operating technologies, including lean manufacturing 5S principles. Understanding the program's importance and knowing how to get started are the most important steps. In Iranian economic environment it is always hard to convince any top management to invest on methodologies like TPM. The reason behind this is that there are very few examples of companies with successful implementation of these methodologies. Since management...
Effect of varying aspect ratio on relative stability for graphene nanoribbon interconnects
, Article Applied Mechanics and Materials, 24 July 2012 through 26 July 2012 ; Volume 229-231 , November , 2012 , Pages 205-209 ; 16609336 (ISSN) ; 9783037855102 (ISBN) ; Faez, R ; Nasiri, S. H ; Davoodi, B ; Sharif University of Technology
2012
Abstract
Achieving dense off-chip interconnection with satisfactory electrical performance is emerging as a major challenge in advanced system engineering. Graphene nanoribbons (GNRs) have been recently proposed as one of the potential candidate materials for both transistors and interconnect. In addition, development is still underway for alternative materials and processes for high aspect ratio (AR) contacts. Studding the effect of varying aspect ratio on relative stability of graphene nanoribbon interconnects is an important viewpoint in performance evaluation of system. In this paper, Nyquist stability analysis based on transmission line modeling (TLM) for GNR interconnects is investigated. In...
Effect of varying dielectric constant on relative stability for graphene nanoribbon interconnects
, Article Applied Mechanics and Materials, 24 July 2012 through 26 July 2012, Kuala Lumpur ; Volume 229-231 , July , 2012 , Pages 201-204 ; 16609336 (ISSN) ; 9783037855102 (ISBN) ; Faez, R ; Nasiri, S. H ; Davoodi, B ; Sharif University of Technology
2012
Abstract
The remarkable properties of graphene nanoribbons (GNRs) make them attractive for nano-scale devices applications, especially for transistor and interconnect. Furthermore, for reduction interconnects signal delay, low dielectric constant materials are being introduced to replace conventional dielectrics in next generation IC technologies. With these regards, studding the effect of varying dielectric constant (e{open}r) on relative stability of graphene nanoribbons interconnect is an important viewpoint in performance evaluation of system. In this paper, Nyquist stability analysis based on transmission line modeling (TLM) for graphene nanoribbon interconnects is investigated. In this...
Bode stability analysis for single wall carbon nanotube interconnects used in 3D-VLSI circuits
, Article World Academy of Science, Engineering and Technology ; Volume 77 , 2011 , Pages 568-571 ; 2010376X (ISSN) ; Faez, R ; Davoodi, B ; Farrokhi, M ; Sharif University of Technology
2011
Abstract
Bode stability analysis based on transmission line modeling (TLM) for single wall carbon nanotube (SWCNT) interconnects used in 3D-VLSI circuits is investigated for the first time. In this analysis, the dependence of the degree of relative stability for SWCNT interconnects on the geometry of each tube has been acquired. It is shown that, increasing the length and diameter of each tube, SWCNT interconnects become more stable
Superhydrophobic home-made polyurethane sponges for versatile and cost-effective oil and water separation
, Article Separation and Purification Technology ; Volume 276 , 2021 ; 13835866 (ISSN) ; Pakzad, H ; Fakhri, M ; Moosavi, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Utilizing 3D and 2D porous materials modified by a superhydrophobic/philic coating for quick removal of oil from water and a continuous process of oil/water separation, respectively, has attracted a lot of attention recently. Here we report the separation capacities of one commercial and three home-made sponges, sprayed by a superhydrophobic coating, for a broad range of oils and solvents. The contact angle of water on the coated sponges is 162.5˚, whereas the pristine sponge shows a contact angle of 91.8˚ (these values are for sponge D which had the highest absorption capacity). We investigate the effects of the density of sponges and the dynamic viscosity of oils and solvents on the...
Traffic improvements in wireless communication networks using antenna arrays
, Article IEEE Journal on Selected Areas in Communications, Piscataway, NJ, United States ; Volume 18, Issue 3 , 2000 , Pages 458-471 ; 07338716 (ISSN) ; Rashid Farrokhi, F ; Liu, K. J. R ; Sharif University of Technology
IEEE
2000
Abstract
A wireless network with beamforming capabilities at the receiver is considered that allows two or more transmitters to share the same channel to communicate with the base station. A novel approach is introduced, which combines the effects of the digital signal processing (adaptive beamforming) at the physical layer with the traffic policies at the network layer on the overall queuing model of a cell. The effect of signal processing on the queuing model of the cell is represented by a parameter in the final cell model. Each cell is modeled by a multiuser/multiserver service facility, where each server is a beamformed channel formed by the cell's base station. From this effective cell model,...
Feasibility analysis of the use of rigid polyurethane foam in modular sandwich panels for rapid assembly structures
, Article International Journal of GEOMATE ; Volume 15, Issue 51 , 2018 , Pages 113-120 ; 21862982 (ISSN) ; Nemati, S ; Sharafi, P ; Yaghmaei, F ; Farrokhi, A ; Sharif University of Technology
GEOMATE International Society
2018
Abstract
Mobile and rapidly assembled structures play an important role in building temporary and semi-permanent accommodations and shelters in post-disaster management. One of the most efficient construction systems that can be used in rapidly assembled buildings is lightweight panelized systems. Use of rapidly assembled panelized systems is becoming very popular for cutting the construction time and transportation costs that make them suitable options for rapid assembly construction. In addition, when acoustic and thermal insulation of buildings is important, foam filled composite sandwich panels are an effective solution. Soft, semi-rigid and rigid Polyurethane (PU) foams, which are first...
Love Wave Propagation in a Functionally Graded Magneto-Electro-Elastic Half-Space with Quadratic Variations
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor)
Abstract
The propagation behavior of Love wave in functionally graded magneto-electro-elastic half-spaces with a quadratic variation is addressed. The magneto-electromechanical coupling factor, the dispersion relations, electric potential, magnetic potential and displacement are obtained analytically for both magneto-electrically open and short conditions. The effect of gradient coefficient on phase velocity, group velocity and magneto-electromechanical coupling factor are plotted and discussed. Research on the wave propagation in magneto-electro-elastic materials is still very limited. This work provides us with a theoretical foundation to design and practically apply SAW devices with high...