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Differentiating Signals Recorded from Rat Brain in Response to Different Olfactory Stimuli
, M.Sc. Thesis Sharif University of Technology ; Karbalaei Aghajan, Hamid (Supervisor)
Abstract
The olfactory sense in rats provides crucial information for identifying food sources, detecting threats, and facilitating social interactions. The olfactory bulb is one of the key brain regions involved in the initial processing of olfactory information and its transmission to higher brain areas for more complex processing. However, more advanced cognitive processes such as evaluation and decision-making rely on interactions between other brain regions. Among these, the striatum, as a part of the basal ganglia, plays a role in reward evaluation, reward-based learning, and shaping behaviors associated with sensory stimuli. This region contributes to learning, decision-making, and action...
Comparing half-metallic, MOKE, and thermoelectric behavior of the CrTiZ (Z = As, P) half-Heuslers: A DFT study
, Article Materials Research Express ; Volume 8, Issue 4 , 2021 ; 20531591 (ISSN) ; Zelati, A ; Boochani, A ; Arman, A ; Mirzaei, S ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
Structural, half-metallic, magneto-optic, and thermoelectric properties of CrTiZ (Z = As, P) half-Heusleres compounds are investigated based on density functional theory. These compounds have mechanical stability in the ferromagnetic state with a high bulk modulus. They are often half-metallic with a large and integer magnetic moment and are very attractive in spintronics, magneto-optics applications. The magnetic moments of CrTiAs and CrTiP were 2.9865 μB and 3.00 μB, respectively, which were attributed to their ferromagnetic phase. Additionally, the positive sign of the phonon branches indicates the dynamic stability of these compounds. Applying both GGA and mBJ approximations, CrTiAs and...
The Effect of Rudder Angle on Ship’s Fuel Consumption
, M.Sc. Thesis Sharif University of Technology ; Khorasanchi, Mahdi (Supervisor) ; Zare, Arman (Co-Supervisor)
Abstract
The aim of this research is to investigate the effect of speed and direction of current on ship fuel consumption. A KCS benchmark model has been numerically studied in calm water and fourteen current and wind conditions with the same speed and different directions to determine how the ship performance is dependent on flow conditions. The model has been simulated in an artificial basin propelled by a single right-handed propeller via a CFD commercial code. Numerical results revealed a linear relationship between the deviation of current and wind from head-sea or following-sea conditions and the rudder angle. The head-sea and following-sea currents and winds increased and decreased the lateral...
Microstructure and optical properties of Au:N doped diamond-like carbon films: effect of working pressure
, Article Surfaces and Interfaces ; Volume 52 , 2024 ; 24680230 (ISSN) ; Mardani, M ; Shafiekhani, A ; Arman, A ; Luna, C ; Sharif University of Technology
2024
Abstract
In recent years, the incorporation of impurities (metallic or non-metallic) into diamond-like carbon films for industrial and biological applications has garnered considerable attention from researchers. In this study, gold nanoparticles and nitrogen impurities were introduced into diamond-like carbon using a co-deposition method involving Radio Frequency Plasma-Enhanced Chemical Vapor Deposition (RF-PECVD) and Radio Frequency Sputtering (RF-sputtering),modifying the working pressure from 14.5 to 19.5 mTorr. X-ray Diffraction (XRD) patterns confirmed the presence of gold nanocrystals in the samples. The surface morphology of the films was analyzed using images obtained from Scanning Electron...
Evaluation of the topographical surface changes of silicon wafers after annealing and plasma cleaning
, Article Silicon ; Volume 12, Issue 11 , 2020 , Pages 2563-2570 ; Ţălu, Ş ; Dallaev, R ; Arman, A ; Sobola, D ; Salerno, M ; Sharif University of Technology
Springer Science+Business Media B.V
2020
Abstract
Purpose: The morphological stability of silicon single crystal wafers was investigated, after performing cleaning surface treatments based on moderate temperature annealing and plasma sputtering. Methods: The wafer surfaces were measured by Tapping mode atomic force microscopy in air, before and after the different treatments. The 3D images were segmented by watershed algorithm identifying the local peaks, and the stereometric parameters were extracted thereof. The analysis of variance allowed to better assess the statistically significant differences. Results: All the resulting quantities were critically discussed. It appeared that the different cleaning treatments affected differently the...
Passive localization of stationary targets: In extremely noisy conditions and asymmetric paths
, Article ISPACS 2012 - IEEE International Symposium on Intelligent Signal Processing and Communications Systems ; 2012 , Pages 385-389 ; 9781467350815 (ISBN) ; Sharif University of Technology
2012
Abstract
A new method for position determination of stationary targets from radio bearings, using triangulation, and based on the partial derivative analysis of bearing error has been proposed. Mathematical derivations have been carried out and a simulation illustrating the effectiveness of the method has been run. It turns out that, the method works best when the noise is excessively high and the traversed path is asymmetric. In such conditions, the method illustrates an error reduction of up to 5% with respect to the Least Square algorithm
Laser diode modulation under large signal conditions
, Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 , Page(s): 1 - 5 ; 9781467356343 (ISBN) ; Sharif University of Technology
2013
Abstract
Large signal behavior of the Laser Diode is analyzed with the aim of finding a qualitative relationship between modulation amplitude and the change in the shape of its transfer function. It is found that, at quasi-static conditions, increasing the amplitude of the modulating signal smoothes out the original piecewise-linear transfer function of the diode. It further shifts the now smoothed knee point to lower DC currents. As the frequency increases, however, these effects become less and less pronounced. In addition, the transfer function becomes rather wavy due to the failure of current density to reach the saturation level necessary for adequate stimulated emission. At even higher...
An investigation of failure analysis of a superheater boiler tube working for 40 months
, Article Canadian Metallurgical Quarterly ; 2023 ; 00084433 (ISSN) ; Sharif University of Technology
Taylor and Francis Ltd
2023
Abstract
In this paper the root cause failure of a super-heater boiler tube is discovered. The tube has been worked in caustic media (pH = 8.9∼9.6) for virtually 40 months. The working temperature and pressure were recorded in the range of 204-315°C and 43 bar, respectively According to the chemical analysis, it was revealed that the tube is in accordance with ASTM A213 Gr T22. The corrosion products of the tube were characterized by EDS, XRF and XRD techniques. Visual inspection indicated that the macro-cavity was promoted on the inner surface of the tube. Also, a drastic wall thinning with gouging marks were observed. As a result of steam blanketing phenomenon, the sodium ions are locally...
An investigation of failure analysis of a superheater boiler tube working for 40 months
, Article Canadian Metallurgical Quarterly ; Volume 63, Issue 4 , 2024 , Pages 1347-1355 ; 00084433 (ISSN) ; Sharif University of Technology
2024
Abstract
In this paper the root cause failure of a super-heater boiler tube is discovered. The tube has been worked in caustic media (pH = 8.9∼9.6) for virtually 40 months. The working temperature and pressure were recorded in the range of 204-315°C and 43 bar, respectively According to the chemical analysis, it was revealed that the tube is in accordance with ASTM A213 Gr T22. The corrosion products of the tube were characterized by EDS, XRF and XRD techniques. Visual inspection indicated that the macro-cavity was promoted on the inner surface of the tube. Also, a drastic wall thinning with gouging marks were observed. As a result of steam blanketing phenomenon, the sodium ions are locally...
The effect of thickness and film homogeneity on the optical and microstructures of the ZrO2 thin films prepared by electron beam evaporation method
, Article Optical and Quantum Electronics ; Volume 53, Issue 8 , 2021 ; 03068919 (ISSN) ; Talebani, N ; Zelati, A ; Ţălu, Ş ; Arman, A ; Mirzaei, S ; Jafari, A ; Sharif University of Technology
Springer
2021
Abstract
In this study, ZrO2 coatings with different thicknesses were grown by the electron beam evaporation technique. The crystalline structure was studied by XRD analysis which suggested the tetragonal and monoclinic phases for ZrO2 coatings. Additionally, the film thickness slightly enhanced the crystallinity. The surface morphology and fractal features were analyzed using Scanning Electron Microscopy (SEM). The surface statistical parameters and the fractal geometry were employed to analyze the impact of the coating thickness and homogeneity on the morphology of the films. The statistical processing and fractal dimension revealed variations in the morphology parameters due to the electron beam...
Electrokinetic Flow in pH-Regulated Solid-State/Soft Micro-Nanochannels
,
Ph.D. Dissertation
Sharif University of Technology
;
Saeedi, Mohammad Hassan
(Supervisor)
;
Mousavi, Ali
(Co-Supervisor)
;
Sadeghi, Arman
(Co-Supervisor)
Abstract
In recent years, advances have been made in the field of miniaturization of the devices (in order to increase their efficiency, lessen the materials needed for the constructions and experiments, reduce costs and energy usage) resulting in the dramatic increase of surface to volume ratio in these devices. This progress has led to the dominance of surface forces which can be used to control very important interface phenomena having a special application such as electrokinetic. Using today’s manufacturing technology; it is possible to construct micro-nanochannels made from different materials such as silicon, glass, quartz, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA) whose...
Influence of film thickness on structural, optical, and electrical properties of sputtered nickel oxide thin films
, Article Microscopy Research and Technique ; Volume 87, Issue 7 , 2024 , Pages 1402-1412 ; 1059910X (ISSN) ; Korpi, A.G ; Karimi, M ; Jurečka, S ; Arman, A ; Luna, C ; Ţălu, Ş ; Sharif University of Technology
2024
Abstract
Utilizing radio frequency magnetron sputtering, we successfully fabricated nickel oxide thin films with different thickness (from 80 to 270 nm), and conducted an in-depth examination of their structural, morphological, optical, and electrical properties. The crystal structure and surface roughness were determined using x-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The XRD analyses showed that the films were composed of cubic nickel oxide, exhibiting a notable orientation along the (200) direction. This crystal texture partially increased when the film thickness reached 270 nm. In addition, a direct correlation between film thickness and crystallite size was...
Simulation of Red Blood Cell mechanical behavior in optical tweezers experiment based on a particle method
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010 ; Volume 2 , 2010 , Pages 325-329 ; 9780791844267 (ISBN) ; Firoozbakhsh, K ; Hasanian, M
2010
Abstract
Optical tweezers provide an accurate measurement technique for evaluating mechanical properties of the living cells and many experimental studies have been done to understand the behavior of cells due to external forces. Numerical studies such as finite element methods have been used in order to simulate mechanical behavior of the Red Blood Cells (RBCs). Recent studies have shown that the particle methods are useful tools to simulate the mechanical behavior of living cells. Since in microscopic scales, using discrete models are preferred than continuum methods, a particle-based method is used to simulate the deformation of RBC which is stretched by optical tweezers. The cytoplasm of RBC is...
Structural, morphological, and optical bandgap properties of ZnS thin films: a case study on thickness dependence
, Article Optical and Quantum Electronics ; Volume 56, Issue 7 , 2024 ; 03068919 (ISSN) ; Sadeghi, M ; Shakoury, R ; Matos, R. S ; da Fonseca Filho, H.D ; Arman, A ; Sharif University of Technology
2024
Abstract
Thin films of zinc sulfide (ZnS) with varying thicknesses have been successfully fabricated using radio frequency magnetron sputtering on glass substrates at a temperature of 300 K. Structural analysis via X-ray diffraction and selected area electron diffraction confirmed the presence of nanocrystalline cubic ZnS phases in the films. The crystallite size, determined from X-ray diffraction lines, ranged between 42 and 55 nm. We also explored the morphological attributes of these surfaces and observed significant changes in both grain shape and size. Our atomic force microscopy analyses revealed that the thinner film displayed a topography marked by thinner, elongated rough peaks. As the film...
Effect of temper rolling and subsequent annealing on texture development and magnetic permeability of semi-processed electrical steel with 2.3 wt.% Si
, Article International Journal of Materials Research ; Volume 109, Issue 10 , 2018 , Pages 930-937 ; 18625282 (ISSN) ; Akbarzadeh, A ; Sharif University of Technology
Carl Hanser Verlag
2018
Abstract
The effect of temper rolling and subsequent annealing on texture development and magnetic properties of semi-processed non grain oriented electrical steel has been investigated. The result shows that 5 % temper rolling and final annealing at 850 8C resulted in strong a-fiber component. The etch-pit technique shows that strain induced boundary migration is responsible for new texture component augmentation. Vibrating sample magnetometery reveals that maximum and minimum magnetic permeability are related to rolling and transverse directions, respectively. Average magnetic permeability is improved to some extent as a result of temper rolling and subsequent annealing. © Carl Hanser Verlag GmbH &...
Evaluation the Effect of Thermo-Mechanical Parameters on Microstructure and Texture of Electrical Steel for Improving Magnetic Permeability
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Dependence of some magnetic properties such as core loss and permeability on temper rolling was studied in this thesis. It is shown that with a proper temper rolling sharper textures are obtained in the electrical steel and the magnetic properties in the longitudinal and traverse directions are improved. By texture analysis, it is shown that because of temper rolling, shear strain on the surface of the sheet is the main factor for abnormal grain growth and shear texture formation on the surface. The result of formation of this texture is enhancement of the {100} intensity and reduction of the {111} intensity, leading to the improvement of the permeability. Temper rolling is always...
Plasma surface functionalization of boron nitride nano-sheets
, Article Diamond and Related Materials ; Volume 77 , 2017 , Pages 110-115 ; 09259635 (ISSN) ; Achour, A ; Solaymani, S ; Islam, M ; Vizireanu, S ; Arman, A ; Ahmadpourian, A ; Dinescu, G ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
On silicon substrates, boron nitride nanosheets (BNNS) consisting of interconnected hexagonal boron nitride nano-layers were produced via chemical vapor deposition process at 1200 °C whose roughness's are at the micrometer- and nanometer-scale. The BNNS were functionalized in argon plasma admixed with ammonia or nitrogen or oxygen. The samples were characterized to investigate the surface chemistry and structural changes after plasma treatment using X-ray photoelectron spectroscope and Micro-Raman spectroscope techniques, respectively. While no significant changes in the surface features, upon plasma treatments of the BNNS, were noticed during SEM and TEM examination, the oxygen functional...
Multiferroic behavior of the functionalized surface of a flexible substrate by deposition of Bi2O3 and Fe2O3
, Article Microscopy Research and Technique ; 2021 ; 1059910X (ISSN) ; Sobola, D ; Ţălu, Ş ; Orudzev, F ; Arman, A ; Kaspar, P ; Dallaev, R ; Ramazanov, G ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
Thin films of bismuth and iron oxides were obtained by atomic layer deposition (ALD) on the surface of a flexible substrate poly(4,4′-oxydiphenylene-pyromellitimide) (Kapton) at a temperature of 250°C. The layer thickness was 50 nm. The samples were examined by secondary-ion mass spectrometry, and uniform distribution of elements in the film layer was observed. Surface morphology, electrical polarization, and mechanical properties were investigated by atomic force microscope, piezoelectric force microscopy, and force modulation microscopy. The values of current in the near-surface layer varied in the range of ±80 pA when a potential of 5 V was applied. Chemical analysis was performed by...
The influence of vertical deflection of the supports in modeling squeeze film damping in torsional micromirrors
, Article Microelectronics Journal ; Volume 43, Issue 8 , 2012 , Pages 530-536 ; 00262692 (ISSN) ; Taghi Ahmadian, M ; Sharif University of Technology
Elsevier
2012
Abstract
The objective of this work is to create an analytical framework to study the problem of squeezed film damping in micromirrors considering the bending of the supporting torsion microbeams. Using mathematical and physical justifications, nonlinear Reynolds equation governing the behavior of the squeezed gas underneath the mirror is linearized. The resulting linearized equation is then nondimensionalized and analytically solved for two cases of the infinitesimal and finite tilting angle of the mirror. The obtained pressure distribution from the solution of the Reynolds equation is then utilized for finding the squeezed film damping force and torque applied to the mirror. The results show that...
Design and analysis of a 3-link micro-manipulator actuated by piezoelectric layers
, Article Mechanism and Machine Theory ; Volume 112 , 2017 , Pages 43-60 ; 0094114X (ISSN) ; Jafarishad, H ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
The purpose of this paper is to design and analyze a 3-link micro-device proposed as a micro-manipulator. This micro-manipulator includes 3 micro-beams as links connected to one another with no conventional or flexural joints. While the structure of the micro-manipulator is monolithic, end-effector workspace is achieved through deflection of links which is actuated by piezoelectric layers. By combining static analysis of the links through a multilayer piezoelectric beam model and kinematic analysis of the micro-manipulator, inverse kinematic has been solved utilizing the Taylor series expansion technique and the perturbation method. The obtained results through the present model reveal that...