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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...
Simulation of SO2 absorption in a venturi scrubber
, Article Chemical Engineering Communications ; Volume 197, Issue 7 , Feb , 2010 , Pages 934-952 ; 00986445 (ISSN) ; Mohebbi, A ; Taheri, A ; Sharif University of Technology
2010
Abstract
In this study, a three-dimensional mathematical model, based on a nonuniform droplet concentration distribution, has been developed to simulate gas absorption in a venturi scrubber. The mass transfer process was illustrated by assuming the liquid phase as a combination of droplets and film. The flow, just as the annular two-phase flow, includes a flow of liquid film layer on the walls and a flow of gas and liquid drops in the core. Peclet number was determined using experimental data reported by Viswanathan et al. (1984) for distribution of droplets across the cross section of the scrubber. The mathematical model for gas absorption was justified by comparing the theoretical predictions with...
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...
The effect of prestrain temperature on kinetics of static recrystallization, microstructure evolution, and mechanical properties of low carbon steel
, Article Journal of Materials Engineering and Performance ; Volume 27, Issue 5 , 2018 , Pages 2049-2059 ; 10599495 (ISSN) ; Karimi Taheri, K ; Karimi Taheri, A ; Sharif University of Technology
Springer New York LLC
2018
Abstract
In this research, the samples of a low carbon steel sheet were rolled up to a thickness prestrain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Microhardness, SEM, and tensile tests were carried out to evaluate the static recrystallization kinetics defined by the Avrami equation, microstructural evolution, and mechanical properties. It was found that the Avrami exponent is altered with change in prestrain temperature and it achieves the value of 1 to 1. 5. Moreover, it was indicated that prestraining at subzero temperature followed by annealing at 600 °C leads to considerable enhancement in tensile properties and kinetics of static...
An investigation on tensile properties of coiled carbon nanotubes using molecular dynamics simulation
, Article Diamond and Related Materials ; Volume 74 , 2017 , Pages 154-163 ; 09259635 (ISSN) ; Karimi Taheri, K ; Karimi Taheri, A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
A coiled carbon nanotube (CCNT) can be formed from the distortion of parent toroidal carbon nanotube with a uniform pitch length and a uniform spring rise angle. In this research molecular dynamics simulation was carried out to assess the tensile properties of three CCNT having indexes of (3,3), (4,4), and (5,5). The results indicated that Stone-Wales defects are necessary for thermodynamic stability of the CCNTs. The stress-strain curves showed that the yield stress, yield strain, and failure strain are decreased with increase in temperature. The force-displacement curves revealed that the spring constant of these materials is highly depended on the tube diameter and rising angle, while it...
Microstructural evolution, mechanical properties, and corrosion resistance of a heat-treated Mg alloy for the bio-medical application
, Article Journal of Magnesium and Alloys ; Volume 7, Issue 1 , 2019 , Pages 80-89 ; 22139567 (ISSN) ; Karimi Taheri, K ; Karimi Taheri, A ; Sharif University of Technology
National Engg. Reaserch Center for Magnesium Alloys
2019
Abstract
During the recent years, some Mg based alloys have extensively been considered as a new generation of degradable and absorbable bio-medical materials. In this work, the Mg–2Zn–1Gd–1Ca (wt%) alloy as a new metallic bio-material was produced by the casting process followed by the heat treatment. The samples of the alloy were solution treated at temperatures of 500, 550, and 600 °C and then quench aged at temperatures of 125, 150, and 175 °C. The results of SEM-EDS examinations indicated that the alloy microstructure consists of α-Mg matrix and the Ca2Mg6Zn3 and Mg3Gd2Zn3 secondary phases. With regard to the results of Vickers hardness test, the temperatures of 500 °C and 150 °C were selected...
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...
A study of hyperelastic models for predicting the mechanical behavior of extensor apparatus
, Article Biomechanics and Modeling in Mechanobiology ; Volume 16, Issue 3 , 2017 , Pages 1077-1093 ; 16177959 (ISSN) ; Karimi Taheri, K ; Narooei, K ; Karimi Taheri, A ; Sharif University of Technology
Springer Verlag
2017
Abstract
In this research, the nonlinear elastic behavior of human extensor apparatus was investigated. To this goal, firstly the best material parameters of hyperelastic strain energy density functions consisting of the Mooney–Rivlin, Ogden, invariants, and general exponential models were derived for the simple tension experimental data. Due to the significance of stress response in other deformation modes of nonlinear models, the calculated parameters were used to study the pure shear and balance biaxial tension behavior of the extensor apparatus. The results indicated that the Mooney–Rivlin model predicts an unstable behavior in the balance biaxial deformation of the extensor apparatus, while the...
Improved industrial induction time-based technique for evaluating kinetic hydrate inhibitors
, Article Frontiers in Chemistry ; Volume 12 , 2024 ; 22962646 (ISSN) ; Tohidi, B ; Ghanbari, B ; Taheri Rizi, Z ; Sharif University of Technology
2024
Abstract
Kinetic hydrate inhibitor laboratory testing before field application is one of the key priorities in the oil and gas industry. The common induction-time-based technique is often used to evaluate and screen for kinetic hydrate inhibitors (KHIs). However, the main challenge relates to the stochastic nature of hydrate nucleation observed in fresh systems, which often results in scattered data on hydrate formation with unacceptable uncertainties. A much more precise KHI evaluation method, called crystal growth inhibition (CGI), provides comprehensive insights into the inhibitory behavior of a kinetic hydrate inhibitor, including both hydrate formation and decomposition. Given that industry does...
Impacts of socially assistive robots on improving the quality of life in children with autism
, Article Encyclopedia of Child and Adolescent Health, First Edition ; Volume 1 , 2023 , Pages 99-125 ; 978-012818873-6 (ISBN); 978-012818872-9 (ISBN) ; Sharif University of Technology
Elsevier
2023
Abstract
Statistics have shown an endemic worldwide increase of Autistic Spectrum Disorders (ASD) since the 1960s. Autistic disorders are characterized by three major behavioral disorders: impaired social interaction, impaired communication, and impaired imagination and social creativity. The usage of Socially Assistive Robots (SAR) in autism screening and treatment has been increasing in recent years. In this chapter, after reviewing the most important findings of using SAR in autism area, I present some of our recent findings on the clinical application of two interactive social humanoid robots (i.e., NAO and ALICE with the Iranian names of Nima and Mina) as medical assistants in the treatment and...
An investigation on microstructure evolution, mechanical properties, and strain aging of Mg-1.8Zn-0.7Si-0.4Ca biomedical alloy processed by equal channel angular pressing
, Article Journal of Materials Engineering and Performance ; Volume 28, Issue 8 , 2019 , Pages 5207-5219 ; 10599495 (ISSN) ; Karimi Taheri, K ; Karimi Taheri, A ; Shaeri, M. H ; Sharif University of Technology
Springer New York LLC
2019
Abstract
The influence of equal channel angular pressing (ECAP) on microstructure and mechanical behavior, as well as, strain aging during ECAP and post-ECAP of Mg-1.8Zn-0.7Si-0.4Ca biomedical alloy was examined. The alloy in solid solution heat-treated condition was processed by ECAP with route BC at 350 and 400 °C. The specimens ECAPed at 350 °C were aged at 125 and 150 °C for different times. The hardness and shear punch test results indicated that performing ECAP at 350 °C for 4 passes increases the hardness and shear strength of the alloy from 48 HV and 110 MPa to 71 HV and 188 MPa, respectively. It was revealed that the average grain size of the alloy decreases from 78 µm to about 3 µm after 4...
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...
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...
The effect of deformation heating on restoration and constitutive equation of a wrought equiatomic NiTi alloy
, Article Journal of Materials Engineering and Performance ; Volume 21, Issue 4 , April , 2012 , Pages 516-523 ; 10599495 (ISSN) ; Karimi Taheri, A ; Karimi Taheri, K ; Sarraf, I. S ; Abbasi, S. M ; Sharif University of Technology
2012
Abstract
In this study, a set of constitutive equation corrected for deformation heating is proposed for a near equiatomic NiTi shape memory alloy using isothermal hot compression tests in temperature range of 700 to 1000 °C and strain rate of 0.001 to 1 s -1. In order to determine the temperature rise due to deformation heating, Abaqus simulation was employed and varied thermal properties were considered in the simulation. The results of hot compression tests showed that at low pre-set temperatures and high strain rates the flow curves exhibit a softening, while after correction of deformation heating the softening is vanished. Using the corrected flow curves, the power-law constitutive equation of...
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...