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Methodologies for developing knowledge management systems: An evaluation framework
, Article Journal of Knowledge Management ; Volume 19, Issue 4 , 2015 , Pages 682-710 ; 13673270 (ISSN) ; Ramsin, R ; Sharif University of Technology
Emerald Group Publishing Ltd
2015
Abstract
Purpose – This paper aims to provide a criteria-based evaluation framework for assessing knowledgemanagement system (KMS) development methodologies. Design/methodology/approach – The evaluation criteria have been elicited based on the features expected from a successful KMS. Furthermore, a number of prominent KMS development methodologies have been scrutinized based on the proposed evaluation framework. Findings – It was demonstrated that the proposed evaluation framework is detailed and comprehensive enough to reveal the strengths and weaknesses of KMS development methodologies. It was also revealed that even though the evaluated methodologies possess certain strong features, they suffer...
Modelling high-pressure plasma using the equivalent circuit model and the mechanisms of photoionization instability
, Article Physica Scripta ; Volume 82, Issue 3 , 2010 ; 00318949 (ISSN) ; Bahrampour, A. R ; Sharif University of Technology
2010
Abstract
In this paper, the main discharge region and the plasma on the pre-ionization section in a TEA-CO2 laser are simulated by a distributed RLC electric circuit. The transmission line method is applied to the nonlinear distributed circuit, and it is approximated by a lumped nonlinear RLC circuit. By this method the governing partial differential equations are reduced to a system of ordinary differential equations. The parameters of the plasma in this laser are obtained by using this model. The possible photoionization instability is presented. To discuss the instability of the plasma, the current density perpendicular to the applied electric field is obtained. Furthermore, the electron...
Sloshing effects on supersonic flutter characteristics of a circular cylindrical shell partially filled with liquid
, Article International Journal for Numerical Methods in Engineering ; 2018 ; 00295981 (ISSN) ; Ovesy, H. R ; Dehghani Firouz Abadi, R ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
This paper aims to revisit the effect of sloshing on the flutter characteristics of a partially liquid-filled cylinder. A computational fluid-structure interaction model within the framework of the finite element method is developed to capture fluid-structure interactions arising from the sloshing of the internal fluid and the flexibility of its containing structure exposed to an external supersonic airflow. The internal liquid sloshing is represented by a more sophisticated model, referred to as the liquid sloshing model, and the shell structure is modeled by Sanders' shell theory. The aerodynamic pressure loading is approximated by the first-order piston theory. The initial geometric...
Experimental investigation of a modular wind tower in hot and dry regions
, Article Energy for Sustainable Development ; Volume 39 , 2017 , Pages 21-28 ; 09730826 (ISSN) ; Bahadori, M. N ; Dehghani Sanij, A. R ; Sharif University of Technology
Elsevier B.V
2017
Abstract
Passive cooling systems such as wind towers or wind catchers can create thermal comfort for building residents in hot and dry regions. This paper introduces an experimental study of a modular design of wind tower called the modular wind tower with wetted surfaces. Air temperature, relative humidity (RH) and airflow velocity parameters were measured at different times and at points when the velocity of the ambient air was zero. The results show that the modular wind tower can decrease the air temperature by an average of 10 °C and increase the relative humidity of airflow in a building by approximately 36% on average. Additionally, the wind tower can create the airflow velocity entering the...
On the Flutter of Swept Taper Wing in Subsonic Compressible Flow Considering Effect of Fuel Sloshing in External Stores
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firoozabadi, R (Supervisor)
Abstract
In the present work, the aeroelastic stability analysis for the swept taper wing and external fuel tank combination system in subsonic compressible flow are represented. The wing structure is modeled by using the Euler-Bernoulli beam theory. Fuel sloshing is modeled by using an equivalent mechanical mass-spring-damper model. Modal analysis technique is used to drive the structural equations of motion of the system. Aeorodynamic of wing is modeled by using index aerodynamic that has been dived by Marzocca and a slender body aerodynamic theory for the external fuel tank are used. For stability analysis, k-method redrived for a case that structural damping there is. The effects of the external...
Resonant light scattering toward optical fiber humidity sensors
, Article Photonic Sensors ; Volume 9, Issue 1 , 2019 , Pages 60-68 ; 16749251 (ISSN) ; Bahrampour, A ; Bahrampour, A. R ; Sharif University of Technology
Springer Verlag
2019
Abstract
The deposition of tetrakis (4-sulonatophenyl) porphyrin (TPPS) thin film on optical fibers presents many possibilities for sensing applications. The J-form aggregation with a narrow and sharp spectral feature at about 490 nm and its sensitivity to humidity have been discussed; a fast change of wavelength occurs according with variation in the humidity level. The reproducibility and high sensitivity of TPPS-coated fibers, along with the capabilities of optical fibers, suggest the device as a good candidate for humidity sensing in harsh environments. © 2018, The Author(s)
Analytical solution of an induced fiber grating relative humidity sensor
, Article Iranian Journal of Science and Technology, Transaction A: Science ; Volume 44, Issue 2 , 2020 , Pages 519-526 ; Rooholamininejad, H ; Bahrampour, A. R ; Sharif University of Technology
Springer
2020
Abstract
In our previous work, a distributed moisture sensor based on the induced long-period fiber grating in the presence of moisture is proposed. The proposed structure is analyzed numerically (Opt Laser Technol 117:126–133, 2019). In this article, due to the axial symmetry and periodic structure of the proposed sensor, the Love’s potential and Fourier series are employed to obtain an analytical solution for the refractive index variation along the sensor versus moisture density. The analytical method reduces the computation time relative to our numerical calculation drastically. The analytical results are in good agreement with those that are obtained by numerical calculations. The analytical...
Development of an aeroelastic model based on system identification using boundary elements method
, Article Aircraft Engineering and Aerospace Technology ; 2021 ; 17488842 (ISSN) ; Borhan Panah, M. R ; Sharif University of Technology
Emerald Group Holdings Ltd
2021
Abstract
Purpose: The purpose of this paper is to analyze the stability of aeroelastic systems using a novel reduced order aeroelastic model. Design/methodology/approach: The proposed aeroelastic model is a reduced-order model constructed based on the aerodynamic model identification using the generalized aerodynamic force response and the unsteady boundary element method in various excitation frequency values. Due to the low computational cost and acceptable accuracy of the boundary element method, this method is selected to determine the unsteady time response of the aerodynamic model. Regarding the structural model, the elastic mode shapes of the shell are used. Findings: Three case studies are...
Experimental investigation of new designs of wind towers
, Article Renewable Energy ; Volume 33, Issue 10 , 2008 , Pages 2273-2281 ; 09601481 (ISSN) ; Mazidi, M ; Dehghani, A. R ; Sharif University of Technology
2008
Abstract
Two new designs of wind towers were tested side by side with a conventional wind tower in the city of Yazd, Iran. All the towers were of identical dimensions. The two new designs were one with wetted column, consisting of wetted curtains hung in the tower column, and the other one with wetted surfaces, consisting of wetted evaporative cooling pads mounted at its entrance. The air temperature leaving the wind towers with evaporative cooling provisions were much lower than the air temperature leaving the conventional design, and its relative humidity much higher. The air-flow rate was reduced slightly in these new towers. It was found that the wind tower with wetted column performs better with...
Fabrication and evaluation of in vitro studies of biodegradable and antibacterial composite scaffolds based on polylactic acid-polycaprolactone-hydroxyapatite reinforced with graphene and zinc oxide nanoparticles for use in orthopedic surgery
, Article Iranian Journal of Materials Science and Engineering ; Volume 19, Issue 2 , 2022 , Pages 1-19 ; 17350808 (ISSN) ; Saadatabadi, A. R ; Asefnejad, A ; Sharif University of Technology
Iran University of Science and Technology
2022
Abstract
Introduction: Fabrication of fully optimized tissue-engineered materials in order to simulating the natural structure, and enhancing the biological properties of damaged tissue is one of the major challenges in biomedical engineering and regeneration medicine. Although polymeric based membranes have revealed noticeable advancements in bone regeneration, their mechanical stiffens, electrical conductivity and bioactivity need to be tolerated. Methods: Therefore, the present study is designed to generate a multifunctional biomaterial based on polylactic acid (PLA)/ polycaprolactone (PCL)/hydroxyapatite (HA) nanocomposite containing zinc oxide (ZnO) and Graphene (Gr) nanoparticles employing...
Evaluating the influence of You Tube advertising for attraction of young customers
, Article Computers in Human Behavior ; Volume 59 , 2016 , Pages 165-172 ; 07475632 (ISSN) ; Khorram Niaki, M ; Ramezani, I ; Sali, R ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Nowadays, we have been faced with an increasing number of people who are spending tremendous amounts of time all around the world on YouTube. To date, the factors that persuade customers to accept YouTube advertising as an advertising medium are not yet fully understood. The present paper identified four dimensions towards YouTube advertising (i.e., entertainment, Informativeness, Customization and irritation) which may be affected on advertising value as well as brand awareness, and accordingly on purchase intention of consumers. The conceptual model hypothesizes that ad value strategies are positively associated with brand awareness, which in turn influence perceived usefulness of You Tube...
Effect of multiphase fluid and functionally graded density fluid on the stability of spinning partially-filled shells
, Article International Journal of Mechanical Sciences ; Volume 140 , 2018 , Pages 109-118 ; 00207403 (ISSN) ; Nikkhah Bahrami, M ; Dehghani Firouz Abadi, R ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The effect of a multiphase fluid, including an arbitrary number of liquid phases, and a functionally graded density fluid on the stability of rotating partially-filled cylindrical shells is investigated. The first-order shear shell theory is used for modeling the structural dynamics of the shell and a 2D model is introduced based on the Navier–Stokes equations, for fluid motion. The multiphase and the functionally graded density fluids are arranged according to the mass density in a steady state condition due to centrifugal forces. Using the boundary conditions between liquid phases and the boundary conditions of the fluid on the cylinder wall, the coupled fluid-structure system model is...
Hydroelastic analysis of two degree of freedom hydrofoil using a reduced-order hydrodynamic model considering unsteady partial sheet cavity flows
, Article Journal of Fluids and Structures ; Volume 81 , 2018 , Pages 116-130 ; 08899746 (ISSN) ; Haddadpour, H ; Dehghani Firouz Abadi, R ; Sharif University of Technology
Academic Press
2018
Abstract
In the present study a new, fast, precise algorithm for studying hydroelastic stability of a typical section with two degrees of freedom (2DOF) is proposed based on the finite element method (FEM), while the partial sheet cavitation effects are considered. For this means, the steady cavity boundary is calculated by some conventional iterative procedures, developed based on the potential flow simulation. Thereafter, assuming that the amplitude and the frequency of the body oscillations are altered so that the cavity length in unsteady flow remains unchanged, the simulation of the unsteady hydrodynamic flow is performed by imposing some velocity fluctuations over the rigid cavity boundary. For...
On understanding the relation of knowledge and confidence to requirements quality
, Article 27th International Working Conference on Requirements Engineering: Foundation for Software Quality, REFSQ 2021, 12 April 2021 through 15 April 2021 ; Volume 12685 LNCS , 2021 , Pages 208-224 ; 03029743 (ISSN) ; 9783030731274 (ISBN) ; Wnuk, K ; Mendez, D ; Gorschek, T ; Ramsin, R ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
[Context and Motivation] Software requirements are affected by the knowledge and confidence of software engineers. Analyzing the interrelated impact of these factors is difficult because of the challenges of assessing knowledge and confidence. [Question/Problem] This research aims to draw attention to the need for considering the interrelated effects of confidence and knowledge on requirements quality, which has not been addressed by previous publications. [Principal ideas/results] For this purpose, the following steps have been taken: 1) requirements quality was defined based on the instructions provided by the ISO29148:2011 standard, 2) we selected the symptoms of low qualified...
A 2.5GHz CMOS fully-integrated ΔΣ-controlled fractional-N frequency synthesizer
, Article Proceedings - 17th International Conference on VLSI Design, Concurrently with the 3rd International Conference on Embedded Systems Design, Mumbai, 5 January 2004 through 9 January 2004 ; Volume 17 , 2004 , Pages 163-167 ; 10639667 (ISSN) ; Sharif University of Technology
2004
Abstract
The design of a fully-integrated ΔΣ -controlled fractional-N frequency synthesizer is described. Using a dual modulus 64/72 prescaler based on injection locking technique and a novel third order digital ΔΣ modulator, we achieved an extremely low power synthesizer in 2.5GHz band.. Total power dissipation of the frequency synthesizer is less than 6mW at a 1.5V supply. The loop bandwidth is optimized to achieve a -123dBc/Hz phase noise at 3MHz offset frequency. The locking time of the loop is less than 30μs
Prediction of in-plane elastic properties of graphene in the framework of first strain gradient theory
, Article Meccanica ; Volume 54, Issue 1-2 , 2019 , Pages 299-310 ; 00256455 (ISSN) ; Mehralian, F ; Dehghani Firouz Abadi, R ; Borhan Panah, M. R ; Rahmanian, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In the present study, the in-plane elastic stiffness coefficients of graphene within the framework of first strain gradient theory are calculated on the basis of an accurate molecular mechanics model. To this end, a Wigner–Seitz primitive cell is adopted. Additionally, the first strain gradient theory for graphene with trigonal crystal system is formulated and the relation between elastic stiffness coefficients and molecular mechanics parameters are calculated. Thus, the ongoing research challenge on providing the accurate mechanical properties of graphene is addressed herein. Using results obtained, the in-plane free vibration of graphene is studied and a detailed numerical investigation is...
Prediction of in-plane elastic properties of graphene in the framework of first strain gradient theory
, Article Meccanica ; Volume 54, Issue 1-2 , 2019 , Pages 299-310 ; 00256455 (ISSN) ; Mehralian, F ; Dehghani Firouz-Abadi, R ; Borhan Panah, M. R ; Rahmanian, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
In the present study, the in-plane elastic stiffness coefficients of graphene within the framework of first strain gradient theory are calculated on the basis of an accurate molecular mechanics model. To this end, a Wigner–Seitz primitive cell is adopted. Additionally, the first strain gradient theory for graphene with trigonal crystal system is formulated and the relation between elastic stiffness coefficients and molecular mechanics parameters are calculated. Thus, the ongoing research challenge on providing the accurate mechanical properties of graphene is addressed herein. Using results obtained, the in-plane free vibration of graphene is studied and a detailed numerical investigation is...
Photocatalytic degradation of vancomycin using titanium dioxide and optimization by central composite design
, Article International Journal of Environmental Science and Technology ; Volume 19, Issue 9 , 2022 , Pages 8957-8968 ; 17351472 (ISSN) ; Yousefinejad, S ; Dehghani, M ; Borghei, S. M ; Javid, A. H ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Conventional wastewater treatment processes are not completely effective in removing vancomycin. In this study, affecting parameters on vancomycin degradation, such as pH, catalyst, initial vancomycin concentration, temperature, and reaction time were investigated simultaneously during a removal process based on titanium dioxide with ultraviolet irradiation in an aqueous solution. Titanium dioxide was synthesized and characterized using X-ray diffraction and scanning electron microscopy. The average size of the synthesized crystals was 4.7 (± 0.2) nm. Design of experiments was done by a central composite design based on the response surface methodology and multiple linear regression was...
Vancomycin removal using TiO2–clinoptilolite/UV in aqueous media and optimisation using response surface methodology
, Article International Journal of Environmental Analytical Chemistry ; 2022 ; 03067319 (ISSN) ; Yousefinejad, S ; Dehghani, M ; Borghei, S. M ; Javid, A. H ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
Investigations have shown the traces of antibiotics in surface water, groundwater, wastewater treatment plants, and drinking water. However, conventional wastewater treatment is not entirely effective for vancomycin degradation. Advanced oxidation is one of the most widespread methods of antibiotic degradation in aqueous media. Vancomycin was quantified by high-performance liquid chromatography. The Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to explore and optimise the effect of the independent variables on vancomycin degradation. Independent variables were as follows: pH (3–11), vancomycin concentration (15–75 mg/L), TiO2–clinoptilolite (25–125 mg in...
Nonlinear dynamics of extensible viscoelastic cantilevered pipes conveying pulsatile flow with an end nozzle
, Article International Journal of Non-Linear Mechanics ; Volume 91 , 2017 , Pages 22-35 ; 00207462 (ISSN) ; Haddadpour, H ; Dehghani Firouz Abadi, R ; Abtahi, H ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
Nonlinear dynamics of an extensible cantilevered pipe conveying pulsating flow is considered in this paper. The fluid flow fluctuates harmonically and exhausts via a nozzle attached to the end of the pipe. Taking into account the extensibility assumption, the coupled nonlinear lateral–longitudinal equations of motion are derived using Hamilton's principle and discretized via Galerkin's method. The adaptive time step Adams algorithm is applied to extract the time response, and then the bifurcation, power spectral density and phase plane maps are plotted for some case studies. Effects of some geometrical parameters such as flow mass, pulsating flow frequency, gravity, nozzle mass and nozzle...