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    Proposed Method for Selecting the Most Suitable Contractor Using Risk Analysis

    , M.Sc. Thesis Sharif University of Technology Shakiba Zahed, Hadi (Author) ; Mortaheb, Momamad Mehdi (Supervisor)
    Abstract
    At present, with some exceptions, the contracts are awarded based on the least proposed price. The records show that this method has not been successful especially for the infrastructure projects. In other words the projects awarded this way have been completed with time and cost overruns. Most of the times, such projects have not satisfied the stakeholders' expectations or have had problems during operation phase. The goal of this research is to suggest a method for selecting the most suitable contractor, considering the proposed price as well as incorporating the delay and other risks based on Contractors' actual past performance in the completed projects. Before selecting the Contractor,... 

    Modeling of semi-solid A356 alloy under upsetting process

    , Article 9th International Conference on Semi-Solid Processing of Alloys and Composites, S2P 2006, Busan, 11 September 2006 through 13 September 2006 ; Volume 116-117 , 2006 , Pages 622-625 ; 10120394 (ISSN); 3908451264 (ISBN); 9783908451266 (ISBN) Shakiba, M ; Aashuri, H ; Sharif University of Technology
    Trans Tech Publications Ltd  2006
    Abstract
    The flow behavior of a semi-solid A356 alloy at high solid fraction was studied. The mushy zone was considered as an effective two-phase, so that the solid continuum can be compressible porous media, and the liquid phase interaction with the solid skeleton was of Darcy type. The semi-solid flow through the upsetting test was modeled in ABAQUS finite element method software. The Gurson yield criterion has been developed for the modeling process of the flow behavior of solid porous medium. Specimens were globulized by a thermomechanical process and then were tested for various percentages of upsetting. The distribution of solid fraction along the radius of the specimens at different height... 

    Modeling of semi-solid A356 alloy under upsetting process

    , Article Solid State Phenomena ; Volume 116-117 , 2006 , Pages 622-625 ; 10120394 (ISSN) Shakiba, M ; Aashuri, H ; Sharif University of Technology
    Trans Tech Publications Ltd  2006
    Abstract
    The flow behavior of a semi-solid A356 alloy at high solid fraction was studied. The mushy zone was considered as an effective two-phase, so that the solid continuum can be compressible porous media, and the liquid phase interaction with the solid skeleton was of Darcy type. The semi-solid flow through the upsetting test was modeled in ABAQUS finite element method software. The Gurson yield criterion has been developed for the modeling process of the flow behavior of solid porous medium. Specimens were globulized by a thermomechanical process and then were tested for various percentages of upsetting. The distribution of solid fraction along the radius of the specimens at different height... 

    Determination and prioritization of criteria to design urban energy resilience conceptual model (part 2)

    , Article International Journal of Environmental Science and Technology ; Volume 20, Issue 9 , 2023 , Pages 9649-9662 ; 17351472 (ISSN) Mohaghegh Zahed, L ; Abbaspour, M ; Sharif University of Technology
    Institute for Ionics  2023
    Abstract
    Currently, approximately 60% of the global population resides in urban areas. Urban energy resilience can be distinguished into two categories: short-term resilience—the ability to cope with natural disasters, and long-term resilience—the ability to withstand the adverse impacts of climate change. In this study, the outcomes of the previous study, which prioritized 34 sub-criteria based on a four-factor classification: technical/infrastructural, built environment, governance, and socio-cultural aspects of both short and long-term approaches, are employed as the basis for the comprehensive resilience management model. The fuzzy analytic hierarchy process is used to quantify each resilience... 

    Investigation of oil recovery and CO2 storage during secondary and tertiary injection of carbonated water in an Iranian carbonate oil reservoir

    , Article Journal of Petroleum Science and Engineering ; Volume 137 , 2016 , Pages 134-143 ; 09204105 (ISSN) Shakiba, M ; Ayatollahi, S ; Riazi, M ; Sharif University of Technology
    Elsevier  2016
    Abstract
    Gas injection process for more oil recovery and in particular CO2 injection is well-established method to increment oil recovery from underground oil reservoirs. CO2 sequestration which takes place during this enhanced oil recovery (EOR) method has positive impact on reducing the greenhouse gas emission which causes global warming. Direct gas injection into depleted oil reservoirs, encounters several shortcomings such as low volumetric sweep efficiency, early breakthrough (BT) and high risk of gas leakage in naturally fractured carbonate oil reservoirs. Carbonated water injection (CWI) has been recently proposed as an alternative method to alleviate the problems associated with gas... 

    Activating solution gas drive as an extra oil production mechanism after carbonated water injection

    , Article Chinese Journal of Chemical Engineering ; Volume 28, Issue 11 , 2020 , Pages 2938-2945 Shakiba, M ; Ayatollahi, S ; Riazi, M ; Sharif University of Technology
    Materials China  2020
    Abstract
    Enhanced oil recovery (EOR) methods are mostly based on different phenomena taking place at the interfaces between fluid–fluid and rock–fluid phases. Over the last decade, carbonated water injection (CWI) has been considered as one of the multi-objective EOR techniques to store CO2 in the hydrocarbon bearing formations as well as improving oil recovery efficiency. During CWI process, as the reservoir pressure declines, the dissolved CO2 in the oil phase evolves and gas nucleation phenomenon would occur. As a result, it can lead to oil saturation restoration and subsequently, oil displacement due to the hysteresis effect. At this condition, CO2 would act as in-situ dissolved gas into the oil... 

    Modeling and Analysis of the Powder Deposition Mechanisms of Selective Laser Sintering Process

    , M.Sc. Thesis Sharif University of Technology Shakiba, Abdorreza (Author) ; Movahedi, Mohamad Reza (Supervisor)
    Abstract
    Selective laser sintering is a technique which uses a laser as the power source to sintering some selected points at a bed of powder in order to create a solid structure. In this research the SLS mechanisms of powder deposition is simulated and surface smoothness and layer density created by each mechanism is computed. For this purpose roller, blade and hopper mechanisms are simulated. For this simulation, polyamide 12 (PA2200) which is a common material is used. In this simulation at first powder specifications are extracted according to the references and for particle shape instead of using the spherical particle shape we use a certain shape that is more close to reality which created by... 

    The effect of conductivity on current distribution in the Hull cell

    , Article Plating and Surface Finishing ; Volume 89, Issue 1 , 2002 , Pages 50-52 ; 03603164 (ISSN) Ghorbani, M ; Sharifabadi, Sh. A ; Zahed, M. N ; Sharif University of Technology
    2002
    Abstract
    In this study, current distribution data were obtained from a controlled variation of electrolyte conductivity, using a 267 mL Hull cell. Current distribution measurement was made using a sectioned electrode. The current density for each strip was calculated by measuring the weight gain of the strips during plating and applying Faraday's Law. Finally, the Hull cell formula was derived by plotting the regression line for current density versus average logarithmic distance along the segmented Hull cell panel. Three systems were studied: acid sulfate copper, all-chloride nickel, and all-chloride zinc. We found that the solution conductivity affects the current distribution. As the conductivity... 

    Determination of Strain Dependent Dynamic Parameters of Unsaturated a Silty Soil During Drying path using Resonant Column-Torsional Shear Device

    , M.Sc. Thesis Sharif University of Technology Zahed Kameh Olya, Vahid (Author) ; Haeri, Mohsen (Supervisor)
    Abstract
    Shear modulus and damping ratio are the most important parameters for evaluating the performance of geotechnical systems under seismic and dynamic loads. According to the definition, secant shear modulus is the slope of the hysteresis shear stress-shear strain loop and damping ratio indicates the dissipation of wave energy during propagation in the soil. These parameters depend on stress state, shear strain and void ratio of the soil. Shear strain amplitude has an important effect on the behavior of shear modulus and damping ratio and it is necessary to study the behavior of these parameters in the range of small to large strains. In addition to dynamic loading, climate change and wet and... 

    The impact of connate water saturation and salinity on oil recovery and CO2 storage capacity during carbonated water injection in carbonate rock

    , Article Chinese Journal of Chemical Engineering ; 2018 ; 10049541 (ISSN) Shakiba, M ; Riazi, M ; Ayatollahi, S ; Takband, M ; Sharif University of Technology
    Chemical Industry Press  2018
    Abstract
    Carbonated water injection (CWI) is known as an efficient technique for both CO2 storage and enhanced oil recovery (EOR). During CWI process, CO2 moves from the water phase into the oil phase and results in oil swelling. This mechanism is considered as a reason for EOR. Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials. Generally, instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon. Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery... 

    The impact of connate water saturation and salinity on oil recovery and CO2 storage capacity during carbonated water injection in carbonate rock

    , Article Chinese Journal of Chemical Engineering ; Volume 27, Issue 7 , 2019 , Pages 1699-1707 ; 10049541 (ISSN) Shakiba, M ; Riazi, M ; Ayatollahi, S ; Takband, M ; Sharif University of Technology
    Chemical Industry Press  2019
    Abstract
    Carbonated water injection (CWI) is known as an efficient technique for both CO2 storage and enhanced oil recovery (EOR). During CWI process, CO2 moves from the water phase into the oil phase and results in oil swelling. This mechanism is considered as a reason for EOR. Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials. Generally, instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon. Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery... 

    Determination and prioritization of criteria to design urban energy resilience conceptual model (Part 1)

    , Article International Journal of Environmental Science and Technology ; Volume 19, Issue 5 , 2022 , Pages 3593-3606 ; 17351472 (ISSN) Mohaghegh Zahed, L ; Abbaspour, M ; Ghodoosi, J ; Sharifi, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    Nowadays, around 70% percent of global energy usage is consumed in urban areas. Undoubtedly, this figure will increase in coming decades due to population rise. As a result, energy resiliency can be considered as an important issue in urban context. Resilience of energy supply in urban areas can be categorized in two approaches, short-term and long-term. Short-term applies to cope with threats such as earthquakes and floods, and long-term applies to deal with impacts of climate change on global warming. In this study, literature review was applied to design questionnaire for expert survey, followed by Fuzzy analytic hierarchy process method to categorize 34 sub-criteria divided under four... 

    An evaluation of the effect of matric suction on the dynamic strain-dependent parameters of an unsaturated silt

    , Article E3S Web of Conferences ; Volume 382 , 2023 ; 25550403 (ISSN) Haeri, S. M ; Sadollahzadeh, B ; Zahed, V ; Bardanis M ; Sharif University of Technology
    EDP Sciences  2023
    Abstract
    This research investigates the influence of matric suction on the variation of shear modulus and damping ratio of a silty soil in very small to medium shear strain levels. A set of laboratory experiments including three bender elements tests in addition to three resonant column-torsional shear tests have been carried out on unsaturated Firuzkuh silt specimens. In this regard, an unsaturated triaxial cell equipped with a set of bender elements and a resonant column-torsional shear device that can apply and control matric suction have been used. All specimens had an initial void ratio of 0.7 and were tested in various matric suctions under a net mean stress of 50 kPa. For this purpose, the... 

    Partially stabilization of Zirconia and its effects on the Magnesia - Spinel refractory properties

    , Article UNITECR '05 - Unified International Technical Conference on Refractories: 9th Biennial Worldwide Congress on Refractories, Orlando, FL, 8 November 2005 through 11 November 2005 ; 2006 , Pages 715-721 ; 1574982656 (ISBN) Kazemi, A ; Nemati, Z. A ; Faghihi Sani, M. A ; Zahed, F ; Sharif University of Technology
    2006
    Abstract
    In this research, Magnesia Spinel refractories were formulated by using sintered magnesia, Tabular and Calcined Alumina and sintered Spinel. The grain size distribution of raw materials was modified, using the Andreessen equation. In order to improve the physical and mechanical properties and corrosion resistance of specimens, none stabilized Zirconia was added to the system. The pressed samples were sintered at 1700°C and the properties were evaluated at room and high temperatures. The formed phases and resultant microstructure were also, analyzed by XRD and SEM. The corrosion test was conducted in two parts. First, the depth of corrosion was measured in two zone, within 0-1mm and 1-2 mm... 

    Advances in heuristic signal processing and applications

    , Book ; Chatterjee, Amitava ; Nobahari, Hadi ; Siarry, Patrick
    Springer  2013
    Abstract
    There have been significant developments in the design and application of algorithms for both one-dimensional signal processing and multidimensional signal processing, namely image and video processing, with the recent focus changing from a step-by-step procedure of designing the algorithm first and following up with in-depth analysis and performance improvement to instead applying heuristic-based methods to solve signal-processing problems. In this book the contributing authors demonstrate both general-purpose algorithms and those aimed at solving specialized application problems, with a special emphasis on heuristic iterative optimization methods employing modern evolutionary and swarm... 

    Short-term durability of GFRP stirrups under wet-dry and freeze–thaw cycles

    , Article Construction and Building Materials ; Volume 398 , 2023 ; 09500618 (ISSN) Shakiba, M ; Hajmoosa, A. H ; Mahmoudi, M ; Bazli, M ; Ebrahimzadeh, M ; Sharif University of Technology
    Elsevier Ltd  2023
    Abstract
    GFRP stirrups are a promising alternative to conventional steel stirrups due to their non-corrosive nature. However, their performance under cyclic exposure to wet-dry and freeze–thaw conditions in seawater needs to be evaluated to ensure their long-term durability and sustainability. This study investigates the tensile strength of glass fibre reinforced polymer (GFRP) stirrups under seawater wet-dry cycles and seawater and tap water freeze–thaw cycles. In total, 220 stirrups in two different shapes, i.e. U and L shapes, and two different diameters, i.e. 6 mm and 8 mm were manufactured, conditioned, and tested under stirrup tensile test. Conditioned stirrups were subjected to 9 months and 18... 

    A case study on the feasibility of using static-cast fibre-reinforced concrete electric poles fully reinforced with glass fibre reinforced polymer bars and stirrups

    , Article Results in Engineering ; Volume 17 , 2023 ; 25901230 (ISSN) Shakiba, M ; Ahmadi, H ; Mortazavi, S. M. R ; Bazli, M ; Azimi, Z ; Sharif University of Technology
    Elsevier B.V  2023
    Abstract
    This study experimentally investigates the structural performance of full-scale reinforced concrete utility poles fully reinforced with glass fibre reinforced polymer (GFRP) bars. The weak bond strength between GFRP bars and concrete in full-scale structures has been addressed by using an innovative anchorage system. Furthermore, fibre-reinforced concrete (FRC) was successfully used to enhance the crack propagations of GFRP-reinforced concrete poles. Three poles were constructed from FRC, while one was constructed with normal concrete (NC) as a benchmark. Polypropylene (PP) and crimped polyolefin-based macro-synthetic (CPO) fibres were used. An innovative anchorage system was used to... 

    Development of an Evolutionary Algorithm Based on Surrogate Models to be used in Multi-disciplinary Design Optimization of a Flying Vehicle

    , M.Sc. Thesis Sharif University of Technology Ghoreishi, Mohaddeseh (Author) ; Nobahari, Hadi (Supervisor)
    Abstract
    In this research, multi-disciplinary design optimization (MDO) of a flying vehicle has been done based on the flight simulation. A meta-heuristic algorithm called Multi-objective Adaptive Real-coded Memetic Algorithm (MARCOMA) has been used for optimization. Since solving a MDO problem is a time consuming process, a RBF neural network has been used in the optimization algorithm as a surrogate model. The new algorithm, called MARCOMA+NN, has been tested with some standard benchmarks. MDO problem has six disciplines consists structure, aerodynamic, propulsion, guidance, control, and fire control. The MDO problem has 31 design variables and two objective functions. The objective functions are... 

    Optimal Design and Real-time Implementation of a Cooperative Guidance Algorithm against a Flying Vehicle

    , M.Sc. Thesis Sharif University of Technology Motie, Mahyar (Author) ; Nobahari, Hadi (Supervisor)
    Abstract
    A cooperative aerial system to defense a Ground Station (GS), against an Incoming aerial Targets (IT) is presented. GS is surrounded by given terrains and a group of homogenous Unmanned Aerial Vehicles (UAVs) are employed using a novel online guidance algorithm in a decentralized manner. The proposed algorithm includes loiter, midcourse and terminal phases. During loiter; UAVs follow an optimal circular path. IT is supposed to approach GS along an optimal low altitude trajectory with respect to the terrains. UAVs are informed the initial position and velocity of IT and they are unaware of IT trajectory. Each UAV decides on whether to engage with IT or not, and shares its decision with other... 

    Synthesis and Characterization of PVDF Magnetic Nanocomposite

    , M.Sc. Thesis Sharif University of Technology Hadi, Mina (Author) ; Forounchi, Massoud (Supervisor)
    Abstract
    PVDF (polyvinylidene fluoride) magnetic nanocomposite films were prepared by solution casting using two types of nanomagnetic particles: (i) magnetic nanoparticles synthesized by using an alkaline solution of mixed ferrous/ferric salts along with oleic acid as a coating agent at 70˚C; (ii) Fe3O4 nanoparticles prepared by hydrolysis of aqueous solution of ferrous/ferric salts with potassium hydroxide at room temprature. Scanning electron microscopy (SEM) showed that the PVDF magnetic nanocomposite had a porous structure with Fe3O4 nanoparticles dispersed inside the porous polymer matrix. The presence of crystalline magnetite within the polymer matrix was confirmed by X-Ray diffraction method...