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mollaei--fouad
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The Role of Socio-Political Institutions in Economic Performance of Developing Countries
, M.Sc. Thesis Sharif University of Technology ; Nili, Masoud (Supervisor)
Abstract
Findings of economics in last decade shows that social and economic institutions have direct influence on economic performance of a society. However, these institutions are determined by the state. In different regimes, the political power is in the hand of different social groups with different preferences and goals; as a result, different social and economic policies and institutions are take place in different political regimes. In this research, we study economic performance of a society under control of two different political regimes: in first, the majority rules the state and in second, there is a totalitarian regime in which; the political power is concentrated in hand of a group of...
A Brief Investigation on the Effects of Metallic and Composite Patches on the Behavior of Aged Parts Using Numerical Methods (FEM) and Lamb Waves Propagation
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
The main purpose of this text is to develop a method for health monitoring of patch-repaired structures. The method consists of usage of piezoelectric wafer active sensors (PWAS) in the mean of stress waves in plate-like structures and processing the obtained results gathered from these sensors using finite element method. During this analysis, effect of different parameters has been investigated by sensitivity analysis methods. The main kind of stress waves that used are lamb wave of different kind. The behavior of main structure due to propagation of symmetric and anti-symmetric modes of lamb wave was investigated. Beginning with finding the results of un-damaged and un-repaired...
Measuring Dielectrophoresis Force Excerted on Polystyrene Micro-Beads using Optical Tweezers
, M.Sc. Thesis Sharif University of Technology ; Seyyed Reihani, Nader (Supervisor)
Abstract
The base of dielectrophoresis(DEP) technique has been demonstrated through electro-dynamic interactions between an applied non-uniform AC electric field and induced distributed dipoles within a polarized. In particle manipulation and/or separation using the DEP method, knowledge of precise DEP force of a particle is essential in designing a DEP device and improving its separation efficiency and accuracy. In most DEP studies related to particle manipulation and/or separation, however their absolute DEP forces remain unknown[2]. Insufficient information regarding the DEP behavior of particles can result in preventing a strategic maneuver for efficient particle manipulation and/or separation...
Finding tuning frequency for symmetric and anti-symmetric lamb waves using FEM
, Article Export | Download | More... 28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012 ; Volume 3 , 2012 , Pages 2412-2416 ; 9781622767540 (ISBN) ; Moosavi, M. R ; Abedian, A ; Golzad, I ; Sharif University of Technology
2012
Abstract
In the area of life assessment, none-destructive methods of inspection and evaluation (NDI/NDE) play important role to ensure if astructure is still healthy enough to get used of. Using ultrasonic stress waves is one of the easiest and cheapest methods of NDI. Accordingly, different modes of lamb wave are mostly of interest..There are various methods for generating lamb waves. One of these methods is using piezoelectric wafer actuator/sensors (PWAS). Accordingly, one of the most important parts of this method is to generate right mode via an appropriate choose of actuating frequency. In this text using a new method for finding tuning frequencies of different lamb wave modes proposed. For...
A simple low pressure method for the synthesis of TiO2 nanotubes and nanofibers and their application in DSSCs
,
Article
Electronic Materials Letters
;
Volume 11, Issue 4
,
July
,
2015
,
Pages 625-632
;
17388090 (ISSN)
; Mashhoun, S
; Mollaei, M
; Molaei, M
; Taghavinia, N
;
Sharif University of Technology
Kluwer Academic Publishers
2015
Abstract
TiO2 nanotubes were synthesized using a modified autoclave-free thermal method from as-prepared initial powders. The size of initial powders (IP) was found to be critical in determining the morphology and crystal structure of the final product. Oleylamine (OA) was used as the polymer agent in the preparation of initial powders with different mol ratios of OA/Ti: 1, 5, and 10. X-ray diffraction analysis depicted that the increase of mole ratio up to 10 resulted in smaller nanoparticles with the sizes of about 8 nm. It was also deliberated that low temperature thermally treated IP showed the characteristic diffraction pattern of titanate phase of nanotubes. Scanning electron...
Proper measurement of pure dielectrophoresis force acting on a RBC using optical tweezers
, Article Biomedical Optics Express ; Volume 10, Issue 11 , 2019 , Pages 5639-5649 ; 21567085 (ISSN) ; Azadbakht, A ; Mollaei, P ; S. Reihani, N. S ; Sharif University of Technology
OSA - The Optical Society
2019
Abstract
The force experienced by a neutral dielectric object in the presence of a spatially non-uniform electric field is referred to as dielectrophoresis (DEP). The proper quantification of DEP force in the single-cell level could be of great importance for the design of high-efficiency micro-fluidic systems for the separation of biological cells. In this report we show how optical tweezers can be properly utilized for proper quantification of DEP force experienced by a human RBC. By tuning the temporal frequency of the applied electric field and also performing control experiments and comparing our experimental results with that of theoretically calculated, we show that the measured force is a...
Soap-film flow induced by electric fields in asymmetric frames
, Article Physical Review E ; Volume 97, Issue 4 , 2018 ; 24700045 (ISSN) ; Nasiri, M ; Soltanmohammadi, N ; Shirsavar, R ; Ramos, A ; Amjadi, A ; Sharif University of Technology
American Physical Society
2018
Abstract
Net fluid flow of soap films induced by (ac or dc) electric fields in asymmetric frames is presented. Previous experiments of controllable soap film flow required the simultaneous use of an electrical current passing through the film and an external electric field or the use of nonuniform ac electric fields. Here a single voltage difference generates both the electrical current going through the film and the electric field that actuates on the charge induced on the film. The film is set into global motion due to the broken symmetry that appears by the use of asymmetric frames. If symmetric frames are used, the film flow is not steady but time dependent and irregular. Finally, we study...
Synthesis and Properties of Porous PZT-PCN Piezoelectric Ceramics
, Ph.D. Dissertation Sharif University of Technology ; Nemati, Ali (Supervisor) ; Bagheri, Reza (Co-Advisor)
Abstract
Although studies have shown interesting piezoelectric and dielectric properties of PZT containing composite piezoelectric ceramics, there has been no systematic investigation on the PZT-PCN, especially on the porous one.In this study, the dense ceramics of 0.8Pb (Zr1/2Ti1/2)O3–0.2Pb(Co1/3Nb2/3)O3 abbreviated to (PZTCN) systems were successfully prepared by the columbitewolframite precursor method via the mixed oxide technique. Porous PZT-PCN ceramics were prepared by burnable plastic sphere process (BURPS) technique with three types of pore forming agents (PFAs), poly vinyl chloride (PVC), stearic acid (SA), and poly methyl methacrylate (PMMA) at different weight percentages(5, 10,and 15...