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ashrafi--elham
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Identifying and Rating Indicators for Measuring Iranian Entrepreneurship Ecosystem based on OECD Framework’s Domains with ANDE Method
, M.Sc. Thesis Sharif University of Technology ; Yavari, Elham (Supervisor) ; Sharif, Hossein (Co-Advisor)
Abstract
“Entrepreneurship ecosystem” is defined as the elements – individuals, organizations or institutions – apart from the individual entrepreneur that are conducive to, or inhibitive of, the choice of a person to become an entrepreneur, or the probabilities of his or her success following launch. Entrepreneurial businesses operate locally or regionally and are therefore subject to local or regional contextual influence. Moreover particularly in larger countries there can exist significant variation in industry structure and economic base across regions, emphasizing the importance of regional focus. Adopting appropriate policies at the regional level need to have a deep and accurate...
A Method for Incremental Learning of Stream Data
, Ph.D. Dissertation Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor)
Abstract
Today, the pace of information generation, fast processing and instant decision-making is increasing. In this regard, one of the main needs in the field of data management and processing is stream data processing. Today's world needs new methods to deal with and analyze these data. Two of the most challenging aspects of data streams are (i) concept drift, i.e. evolution of data stream over time, which requires the ability to make timely decisions against the high speed of receiving new data; (ii) limited memory storage and the impracticality of using memory due to the large amount of data. Clustering is one of the common methods for processing data streams, without having basic knowledge...
Winner Strategies in a Simulated Stock Market
, Ph.D. Dissertation Sharif University of Technology ; Zamani, Shiva (Supervisor) ; Yavari, Elham (Supervisor)
Abstract
In this study, we explore the dynamics of the stock market using an agent-based simulation platform. Our approach involves creating a multi-strategy market where each agent considers both fundamental and technical factors when determining their strategy. The agents vary in their approach to these factors and the time interval they use for technical analysis. Our findings indicate that investing heavily in reducing the value–price gap was a successful strategy, even in markets where there were no trading forces to reduce this gap. Furthermore, our results remain consistent across various modifications to the simulation’s structure
Droplet condensation on chemically homogeneous and heterogeneous surfaces
, Article Journal of Applied Physics ; Volume 120, Issue 12 , 2016 ; 00218979 (ISSN) ; Moosavi, A ; Sharif University of Technology
American Institute of Physics Inc
2016
Abstract
Nucleation and growth of condensing droplets on horizontal surfaces are investigated via a 2-D double distribution function thermal lattice Boltzmann method. First, condensation on completely uniform surface is investigated and different mechanisms which cause dropwise and filmwise condensation are studied. The results reveal the presence of cooled vapor layer instability in the condensation on completely smooth surfaces. In the second step, condensation on chemically heterogeneous surfaces is investigated. Moreover, the effect of non-uniformity in the surface temperature is also studied. The results indicate that the vapor layer instability and the nucleation start from the heterogeneities....
Biomass Separation in Moving Bed Biofilm Reactors (MBBR) by Natural And Innovative Filters
, M.Sc. Thesis Sharif University of Technology ; Borgheei, Mahdi (Supervisor)
Abstract
The application of membranes for separate of particles in mainly microbial flacs , are fast growing in biological treatment systems. Membrane bioreactors are now considered as one of the major new processes in wastewater treatment. However , membranes are expensive and costly. This study is carried out to test an innovative , locally made filters for separation of flocs in an MBBR reactor. This innovative filter is replacing a traditional settling tank. This type of filters is made very cheaply and has important advantages in installing and operation. Experiments were carried out in a laboratory scale MBBR unit. A filter unit consisting of 3 innovative filter tubes were placed and the...
Continuous-thrust Trajectory Optimization in the Binary Asteroids System
, M.Sc. Thesis Sharif University of Technology ; Asadian, Nima (Supervisor)
Abstract
In this thesis, the optimal trajectories of a spacecraft in the binary asteroids system is studied. The objective functions of optimal trajectories in these system are the maximum coverage of the asteroids surface and minimum time and fuel consumption. For this purpose, the dynamic of binary system is modeled. The binary system of 1999 KW4 is selected as a case study. The ellipsoid-sphere model is a good approximation for the case of this study. In this model, the asteroids orbit in a circular orbit around each other in a spin-spin-orbit resonance configuration, in which the asteroids’ rotational velocity is equal to orbital mean motion. Then, the equations of motion of the spacecraft as the...
Applying Gamification in Corporate Entrepreneurship Culture, Specially Missionary Organizations; Through SafirFilm Case Study
, M.Sc. Thesis Sharif University of Technology ; Yavari, Elham (Supervisor) ; Banki, Sara ($item.subfieldsMap.e)
Abstract
Although existing literature on organizational culture and its change process contains meaningful and rich theories but our studies show that there is no perfect and detailed framework on linking organizational culture change and corporate entrepreneurship culture. In addition to that, Gamification –defined as taking the game design elements into non-game contexts– is a fruitful and academically rich research area. Fortunately an idea proposed recently to explain a method for enhancements in organizational culture in general, and in corporate entrepreneurship culture in particularby Yavari and Jafarian based on using game mechanisms. In their paper "A Gamification-Based Method for Corporate...
New correlation for calculating natural gas Z-factor
, Article Hydrocarbon Processing ; Volume 89, Issue 10 , 2010 ; 00188190 (ISSN) ; Ghotbi, C ; Sharif University of Technology
2010
Droplet condensation and jumping on structured superhydrophobic surfaces
, Article International Journal of Heat and Mass Transfer ; Volume 134 , 2019 , Pages 680-693 ; 00179310 (ISSN) ; Moosavi, A ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A complete cycle of droplet nucleation, growth, coalescence and jumping on different textured hydrophobic and superhydrophobic surfaces is studied for the first time, using a 2-D double distribution function thermal lattice Boltzmann method. First, droplet nucleation mechanism on smooth and rough surfaces is studied in detail. The results reveal the presence of cooled vapor layer instability in the condensation on completely smooth surfaces. However, on the rough surfaces and near the roughness a completely different mechanism is observed and the nucleation occurs on the roughness wedges. Also, the condensation on different textured surfaces with nominal contact angles θa=90°,120°,155° is...
An Investigation on the Behavior of Bolted Connections using Friction Drilling in Shear and Tension
, M.Sc. Thesis Sharif University of Technology ; Ahmadizadeh, Mehdi (Supervisor)
Abstract
Friction drilling or flow drilling is a method of making holes in metal sheets, in which the material is pushed with the aid of heat from friction. This procedure allows making holes in sheet metal, with a sleeve formed as the hole is created. This sleeve is then threaded and used as the nut, thus eliminating the need for access to the interior faces of hollow steel sections. On the other hand, with the development of advanced manufacturing techniques, larger and thicker hollow structural sections are becoming more popular in mid-rise and multistory structures. onsequently, flow drilling can be considered as a viable alternative for traditional drilling techniques, where the material is...
A novel management scheme to reduce emission produced by power plants and plug-in hybrid electric vehicles in a smart microgrid
, Article International Journal of Environmental Science and Technology ; Volume 17, Issue 5 , 2020 , Pages 2529-2544 ; Soleymani, S ; Mehdi, E ; Sharif University of Technology
Springer
2020
Abstract
Recently, with the growth and development of distributed generation (DGs) and energy storage systems (ESSs), as well as smart control equipment, microgrids (MGs) have been developed. Microgrids are comprised of a limited number of constitutive parts, including loads, DGs, ESSs, and electric vehicles (EVs). This paper presents a novel scheme to manage active and reactive powers, based on DGs, ESSs, and EVs to reduce the total operation cost including power generation and emission costs. Simultaneous management of active and reactive power makes it possible to consider grid operation constraints together. In the proposed schedule, the vehicles are assumed to be plug-in hybrid electric...
Recycling of Cobalt with the form of Cobalt Nano Oxide from Spent Li-ion Batteries
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
One of the most important methods for recycling of spent Li-ion batteries is acid leaching that various parameters affect it. In this work, influences of effective parameters on the percent of cobalt and lithium recovery with application of design of experiments (response surface methodology-central composite) were investigated and then cobalt nano oxide as the by-product synthesized by pulsing lectrolysis. In the first Phase, effects of parameters such as sulfuric acid oncentration: 2-6 molar, hydrogen peroxide volume percent: 5-10%, S/L ratio: 20-50 g/L and temperature: 50-80°C on cobalt and lithium recovery were investigated and finally an adequate model presented. For all experiments,...
Two-dimensional modeling of functionally graded viscoelastic materials using a boundary element approach
, Article Advanced Materials Research, 7 January 2012 through 8 January 2012 ; Volume 463-464 , January , 2012 , Pages 570-574 ; 10226680 (ISSN) ; 9783037853634 (ISBN) ; Bahadori, M. R ; Shariyat, M ; Sharif University of Technology
2012
Abstract
In this paper, a 2D boundary element approach able to model viscoelastic functionally graded materials (FGM) is presented. A numerical implementation of the Somigliana identity for displacements is developed to solve 2D problems of exponentially graded elasticity. An FGM is an advanced material in which its composition changes gradually resulting in a corresponding change in properties of the material. The FGM concept can be applied to various materials for structural and functional uses. Our model needs only the Green's function of nonhomogeneous elastostatic problems with material properties that vary continuously along a given dimension. We consider the material properties to be an...
Modeling of viscoelastic solid polymers using a boundary element formulation with considering a body load
, Article Advanced Materials Research, 7 January 2012 through 8 January 2012 ; Volume 463-464 , January , 2012 , Pages 499-504 ; 10226680 (ISSN) ; 9783037853634 (ISBN) ; Bahadori, M. R ; Shariyat, M ; Sharif University of Technology
2012
Abstract
In this work, a boundary element formulation for 2D linear viscoelastic solid polymers subjected to body force of gravity has been presented. Structural analysis of solid polymers is one of the most important subjects in advanced engineering structures. From basic assumptions of the viscoelastic constitutive equations and the weighted residual techniques, a simple but effective boundary element formulation is implemented for standard linear solid (SLS) model. The SLS model provides an approximate representation of observed behavior of a real advanced polymer in its viscoelastic range. This approach avoids the use of relaxation functions and mathematical transformations, and it is able to...
A new low voltage, high PSRR, CMOS bandgap voltage reference
, Article 2008 IEEE International SOC Conference, SOCC, Newport Beach, CA, 17 September 2008 through 20 September 2008 ; 2008 , Pages 345-348 ; 9781424425969 (ISBN) ; Atarodi, M ; Chahardori, M ; Sharif University of Technology
2008
Abstract
A new low voltage bandgap reference (BGR) in CMOS technology, with high power supply rejection ratio (PSRR) is presented. The proposed circuit uses a regulated current mode structure and some feedback loops to reach a low voltage, low power and high PSRR voltage reference. The circuit was designed and simulated in 0.18um CMOS technology, with a power supply of 1.4 volt. The results show PSRR is 65dB at 1MHz and the output voltage variation versus temperature (-40 to 140) is less than 0.1%. This circuit shows robustness against process variation. ©2008 IEEE
Numerical Investigation of Formation and Growth of Steam Condensing Droplets on Nanostructured Superhydrophobic Surface Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Condensation is one of the main processes in environment and engineering systems, including thermal power plants, desalination systems and air conditioners. Thus, improvement of its performance can lead to decrease of energy consumption and the resulting air pollutions. Recently, using nanotechnology and new coating methods, there have been great researches on stable superhydrophobic surfaces and using theme as condensing surfaces which because of jumping droplet phenomena can increase condensation performance. Because of the great influence of wetting and structure properties of surfaces on condensation, in this study nucleation and growth of condensing droplets on smooth and structured...
Proposing an Appropriate Lateral Load Pattern for Push-over Analysis of Steel Moment Resisting Frame Structures with Mass Irregularity in Height
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofouei, Fayyaz (Supervisor)
Abstract
The irregularity in structures is divided into two categories of irregularity in vertical and irregularity in plan. The irregularity in vertical can be caused by ultra-change in dynamic properties of the structure such as mass, stiffness or strength. Research studies indicate that this irregularity leads to intensify the applied damages to structures in severe earthquakes. In general, nonlinear dynamic procedure (NDP) can provide more realistic results than nonlinear static procedures (NSPs). That is due to consideration of higher modes effects and the shifts in inertia load pattern as the structural system experiences nonlinear behavior. Nowadays, due to complexity of nonlinear dynamic...
Experimental and numerical study on choosing proper pulse shapers for testing concrete specimens by split hopkinson pressure bar apparatus
, Article Construction and Building Materials ; Volume 125 , 2016 , Pages 326-336 ; 09500618 (ISSN) ; Naghdabadi, R ; Ashrafi, M. J ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Dynamic behavior of concrete specimens is investigated experimentally and numerically by split Hopkinson pressure bar (SHPB) tests. In order to accurately determine dynamic properties of brittle materials such as concrete, specimens should be subjected to particular pulse loading that can be generated by using pulse shapers. Choosing proper pulse shaper dimensions helps to obtain dynamic stress equilibrium, achieve constant strain rate and minimize pulse oscillation in the concrete specimens. To this end, SHPB tests are performed for concrete specimens and effective parameters on shaping pulses such as striker bar velocity, diameter and thickness of the pulse shaper are studied...
Enhancement of bond characteristics of ribbed-surface GFRP bars with concrete by using carbon fiber mat anchorage
, Article Construction and Building Materials ; Volume 134 , 2017 , Pages 507-519 ; 09500618 (ISSN) ; Bazli, M ; Vatani Oskouei, A. V ; Sharif University of Technology
2017
Abstract
The bond of fiber-reinforced polymer (FRP) reinforcement is expected to be more sensitive to the strength and geometry of the ribs than conventional steel reinforcement. In this study, the effect of carbon fiber mat anchorage on the pullout behavior of glass fiber-reinforced polymer (GFRP) bars embedded in normal concrete is studied. The studied parameters were the compressive strength of the concrete (16 MPa, 24 MPa, and 37 MPa), and, the length and diameter of the anchorage. In total, 15 variables were studied. Ribbed GFRP bars with 10 mm nominal diameter and 80 mm embedment length, ld, (which is 8 times the bar diameter) were considered. Based on the results for concretes with the...
Tensile properties of GFRP laminates after exposure to elevated temperatures: Effect of fiber configuration, sample thickness, and time of exposure
, Article Composite Structures ; Volume 238 , 2020 ; Bazli, M ; Jafari, A ; Ozbakkaloglu, T ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This study investigates the tensile properties of various GFRP laminates after exposure to elevated temperatures. Fiber configuration, exposure temperature and laminate thickness were considered as the test variables. A total number of 180 specimens were tested in tension to obtain the mechanical properties of GFRP laminates. Alongside the mechanical tests, SEM analyses were conducted on selected samples before testing to investigate the resin, fiber, and their interface damages. Regardless of the sample type, it was generally observed that the reduction rate in the tensile strength increased with an increase in the exposure time and a decrease in the laminates’ thickness. The results of...