Multi-Variable Optimization of Off-Center Bracing System

, M.Sc. Thesis Sharif University of Technology Shamshiri Guilvaee, Missagh (Author) ; Esmaeil Pourestekanchi, Homayun (Supervisor)

Abstract

Since the advent of earthquake engineering, several methods have been created to repel earthquake forces. One of these methods is to decrease lateral stiffness of structure at its base level. Some systems, such as base isolations which are installed at the base level of structures can provide this softness. In recent years a new kind of bracing system named geometrical (off-center) bracing system has been presented with three convergent members that can increase the main period of structure by applying high displacement at first floor in order to prevent high frequencies from entering structures. Despite of previous researches, in this study the mentioned bracing system has been assessed...

Magnetic Nanocomposites Based on Bio-Degradable Polylactic Acid

, M.Sc. Thesis Sharif University of Technology Shamshiri, Soodeh (Author) ; Frounchi, Masoud (Supervisor)

Abstract

In this work, magnetite (Fe3O4) nanoparticles with an average siz21.9nm
modified by oleic acid were prepared by the coprecipitation method, which can linked well with organic molecules because of the presence of C-O-C on their surface. Then magnetic poly(lactic acid) (PLA)/ poly(ethylene glycol) (PEG) microspheres were prepared by the single emulsion solvent evaporation technology. The incorporation of magnetit nanoparticles and dox into the PLA matrix was confirmed by FTIR. XRD and VSM confirmed the existence of MNPs in the microspheres which maintained superparamagnetic behavior with a saturation magnetization of 50.69 emu/g.Electron microscopy SEM showed that the magnetic microspheres...

Controlled release of doxorubicin from electrospun PEO/chitosan/graphene oxide nanocomposite nanofibrous scaffolds

, Article Materials Science and Engineering C ; Volume 48 , March , 2015 , Pages 384-390 ; 09284931 (ISSN) Ardeshirzadeh, B ; Aboutalebi Anaraki, N ; Irani, M ; Roshanfekr Rad, L ; Shamshiri, S ; Sharif University of Technology

Elsevier Ltd 2015

Abstract

Polyethylene oxide (PEO)/chitosan (CS)/graphene oxide (GO) electrospun nanofibrous scaffolds were successfully developed via electrospinning process for controlled release of doxorubicin (DOX). The SEM analysis of nanofibrous scaffolds with different contents of GO (0.1, 0.2, 0.5 and 0.7 wt.%) indicated that the minimum diameter of nanofibers was found to be 85 nm for PEO/CS/GO 0.5% nanofibers. The π-π stacking interaction between DOX and GO with fine pores of nanofibrous scaffolds exhibited higher drug loading (98%) and controlled release of the DOX loaded PEO/CS/GO nanofibers. The results of DOX release from nanofibrous scaffolds at pH 5.3 and 7.4 indicated strong pH dependence. The...

Estimation of flow rates of individual phases in an oil-gas-water multiphase flow system using neural network approach and pressure signal analysis

, Article Flow Measurement and Instrumentation ; Volume 66 , 2019 , Pages 28-36 ; 09555986 (ISSN) Bahrami, B ; Mohsenpour, S ; Shamshiri Noghabi, H. R ; Hemmati, N ; Tabzar, A ; Sharif University of Technology

Elsevier Ltd 2019

Abstract

Up until now, different methods, including; flow pressure signal, ultrasonic, gamma-ray and combination of them with the neural network approach have been proposed for multiphase flow measurement. More sophisticated techniques such as ultrasonic waves and electricity, as well as high-cost procedures such as gamma waves gradually, can be replaced by simple methods. In this research, only flow parameters such as temperature, viscosity, pressure signals, standard deviation and coefficients of kurtosis and skewness are used as inputs of an artificial neural network to determine the three phase flow rates. The model is validated by the field data which were obtained from separators of two oil...