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azizpour-shirsavar--milad
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Transmission of High Quality Video over Mobile Ad hoc Networks
, M.Sc. Thesis Sharif University of Technology ; Ghanbari, Mohammad (Supervisor)
Abstract
Video communications over mobile ad hoc networks is increasingly deployable as these networks become deployed in various applications such as disaster recovery. Error-prone nature of the mobile ad hoc networks and the vulnerability of compressed video to packet losses have brought many challenges to realize video transmission over MANETs. In this thesis, it is tried to achieve a good quality of service by resilient video coding and multipath transmission over mobile ad hoc networks. To generate error resilient video, a hybrid method is used by combining scalable video coding and multiple description video coding techniques. First, the video sequence is coded to two layers and then each layer...
Design and Analysis of A Business Model Canvas Considering Entrepreneurship and New Product Development in a Fmcg Ecosystem
, M.Sc. Thesis Sharif University of Technology ; Fatahi Valilai, Omid (Supervisor)
Abstract
The business model is very important, as many researchers in this field believe that the success or failure of a business is highly dependent on right design and application of this model. In most recent innovation studies, application of innovation in business models or developing an innovative business model itself is one of the main factors to enable an organization to have stable status in the competitive market. This is unlike the traditional believes, which technology and process were the main motivators behind organization to stand out in competitive market. Designing a proper business model requires a system thinking approach, which considers both internal interactions factors, and...
Theoretical and industrial aspects of amine reclaiming unit to separate heat stable salts
, Article Separation and Purification Technology ; Volume 237 , 2020 ; Moradi, M ; Rostami, A ; Azizpour, H ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this study, a thermal vacuum distillation amine reclaimer unit was industrially and theoretically investigated to remove HSS from a salty amine stream. The presence of ions in the salty amine solution limits application of computer simulation tools to study the process. A thermodynamic equivalent scheme was used for thermal vacuum distillation amine reclaimer, for first time and the simulation results were totally conformed to experimental and industrial data. The effect of critical parameters namely reclaimer vacuum pressure, re-circulation flow rate and HSS amount on performance of thermal amine reclaiming was investigated based on increasing amine solution quality, amine recovery,...
Molecular Simulation of Adsorption of Surface-Modified Silica Nanoparticles at Liquid-Liquid Interfaces
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor)
Abstract
With rising oil prices and predictions about the future of hydrocarbon reserves, issues of enhanced oil recovery and optimal production of existing reservoirs are of particular importance. In this study, molecular dynamics simulation was used to study the absorption of silica nanoparticles with surface groups at the interface of water and decane. The effect of surface chemistry of silica nanoparticles on the interface properties of water-decane with changing the surface groups was simulated. The initial surface factor of nanoparticle is hydroxyl (OH), which is called a hydrophilic surface agent. Nanoparticles were modified by methyl and ethyl surface agents to increase the hydrophobicity and...
Does the short-term boost of renewable energies guarantee their stable long-term growth? Assessment of the dynamics of feed-in tariff policy
, Article Renewable Energy ; Volume 159 , October , 2020 , Pages 1252-1268 ; Hamed Shakouri, G ; Mashayekhi, A. N ; Kazemi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Feed-in tariff (FiT) is one of the most efficient ways that many governments throughout the world use to stimulate investment in renewable energies (REs) technology. For governments, financial management of the policy could be challenging as it needs a considerable amount of budget to support RE producers during the long remuneration period. In this paper, it has been illuminated that the early growth of REs capacity could be a temporary boost. And the socio-economic structure of the system will backlash the policy if some social mechanisms are not considered. Social tolerance for paying REs tax and potential investors’ trust emanated from budget-related mechanisms -which have rarely been...
Fluid Suspended Films in Present of Electric Field and Voltage
, Ph.D. Dissertation Sharif University of Technology ; Amjadi, Ahmad (Supervisor) ; Ejtehadi, Mohammad Reza ($item.subfieldsMap.e)
Abstract
Scientists want to know how they can control fluids motion. They use electric fields for controlling the fluids in different dimensions. In small size, application of electric fields is very important because of biological applications. We use electric current and field for rotating freely suspended films. Here, we study soap, polar and non-polar liquids, MBBA liquid crystal and ferrofluids films. We show that the surface charge plays the crucial role in rotating the films.We study the correlation between rotation of a film and different physical quantities.Our experiments confirm that dipole moments of fluid molecules do not show a clear effect on the rotation. Increasing the dipole moment...
Electrically rotating suspended films of polar liquids
, Article Experiments in Fluids ; Volume 50, Issue 2 , August , 2011 , Pages 419-428 ; 07234864 (ISSN) ; Amjadi, A ; Tonddast Navaei, A ; Ejtehadi, M. R ; Sharif University of Technology
2011
Abstract
Controlled rotation of a suspended soap water film, simply generated by applying an electric field, has been reported recently. The film rotates when the applied electric field exceeds a certain threshold. In this study, we investigate the phenomenon in films made of a number of other liquids with various physical and chemical properties. Our measurements show that the intrinsic electrical dipole moments of the liquid molecules seems to be vital for the corresponding film rotation. All the investigated rotating liquids have a molecular electric dipole moment of above 1 Debye, while weakly polar liquids do not rotate. However, the liquids investigated here cover a wide range of physical...
Induced soap-film flow by non-uniform alternating electric field
, Article Journal of Electrostatics ; Volume 73 , February , 2015 , Pages 112-116 ; 03043886 (ISSN) ; Ramos, A ; Amjadi, A ; Taherinia, J ; Mashhadi, M ; Nejati, A ; Sharif University of Technology
Elsevier
2015
Abstract
Fluid flows generated on soap films by non-uniform alternating electric fields are studied. Two parallel metal rods subjected to an AC voltage are placed perpendicular to the soap film, which is anchored in a dielectric frame. The fluid flow is generated by electrohydrodynamic induction. At very low signal frequencies there is induced surface charge, but there is no tangential electric field at the surface, so there is no force and no flow. Fluid flow is observed increasing the frequency, when there are both surface charge and tangential electric field. The flow velocity increases with decreasing thickness of the soap film
Rotation induced by uniform and non-uniform magnetic fields in a conducting fluid carrying an electric current
, Article RSC Advances ; Volume 6, Issue 113 , 2016 , Pages 112641-112645 ; 20462069 (ISSN) ; Nasiri, M ; Amjadi, A ; Nejati, A ; Sobhani, S.O ; Habibi, M ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
We study the dynamics of a conducting fluid carrying (i) a uniform current in the presence of a non-uniform magnetic field or (ii) carrying a non-uniform current in the presence of a uniform magnetic field, using particle image velocimetry (PIV). Our results show that the average angular velocity of the induced rotation has a power-law dependence on the electric current passing through the fluid with an exponent ≈2/3, in excellent agreement with our simulation results, for the same system. To explain the experimental observations we explore all possibilities for inducing rotation in a fluid carrying an electric current. Our theoretical discussion indicates two scenarios wherein applying...
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...
Rotational regimes of freely suspended liquid crystal films under electric current in presence of an external electric field
, Article Microfluidics and Nanofluidics ; Volume 13, Issue 1 , 2012 , Pages 83-89 ; 16134982 (ISSN) ; Amjadi, A ; Ejtehadi, M. R ; Mozaffari, M. R ; Feiz, M. S ; Sharif University of Technology
2012
Abstract
The electrohydrodynamic (EHD) vortices produced by an electric current in freely suspended liquid crystal (LC) films of N-(4-methoxybenzylidene)-4- butylaniline (MBBA), convert to a pure rotation in the presence of external electric field (E ext) perpendicular to the current direction. Here, the direction and strength of the rotation are precisely under control by our self-made device called "liquid-film motor". In this paper, we present experimental observations of the EHD fluid flow when external electric field varies from zero to a value in which pure rotation on the liquid crystal (LC) film is observed. We also show experimentally that the presence of external electric field causes a...
Micro helical polymeric structures produced by variable voltage direct electrospinning
, Article Soft Matter ; Volume 7, Issue 22 , 2011 , Pages 10548-10551 ; 1744683X (ISSN) ; Iraji Zad, A ; Abdollahzadeh, I ; Shirsavar, R ; Bonn, D ; Ejtehadi, R ; Sharif University of Technology
2011
Abstract
Direct near field electrospinning is used to produce very long helical polystyrene microfibers in water. The pitch length of helices can be controlled by changing the applied voltage, allowing the production of both microsprings and microchannels. Using a novel high frequency variable voltage electrospinning method we determined the helix formation speed and compared the experimental buckling frequency to theoretical expressions for viscous and elastic buckling. Finally we showed that the new method can be used to produce new periodic micro and nano structures
Advancement of sensor integrated organ-on-chip devices
, Article Sensors (Switzerland) ; Volume 21, Issue 4 , 2021 , Pages 1-44 ; 14248220 (ISSN) ; Hartse, B. X ; Niaraki Asli, A. E ; Taghavimehr, M ; Hashemi, N ; Abbasi Shirsavar, M ; Montazami, R ; Alimoradi, N ; Nasirian, V ; Ouedraogo, L. J ; Hashemi, N. N ; Sharif University of Technology
MDPI AG
2021
Abstract
Organ-on-chip devices have provided the pharmaceutical and tissue engineering worlds much hope since they arrived and began to grow in sophistication. However, limitations for their applicability were soon realized as they lacked real-time monitoring and sensing capabilities. The users of these devices relied solely on endpoint analysis for the results of their tests, which created a chasm in the understanding of life between the lab the natural world. However, this gap is being bridged with sensors that are integrated into organ-on-chip devices. This review goes in-depth on different sensing methods, giving examples for various research on mechanical, electrical resistance, and bead-based...