Loading...
Search for:
ebrahimi--shahab
0.249 seconds
Total 470 records
The Effect of Compatibilizer and Short Glass Fiber on Microstructure and Mechanical Properties of PBT/PC Blend
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor)
Abstract
In this research, we studied the effect of compatibilizer and short glass fiber on microstructure and mechanical properties of PBT/PC blends. Fisrt, Antioxidants and sodium pyrophosphate dibasic were used to suppress transesterification in PBT/PC Blend. The results showed that best composition occur when both of them are used. In the next step, we used 3%wt MBS (methyl methacrylate-butadiene-styrene) and saw that this weight percent of this compatibilizer doesn’t useful. Moreover addition of short glass fiber to PBT/PC was examined and the results showed that mechanical properties of composite are extensively increased. Also in this step, we proved this idea that we can replace some of PBT...
Reconfigurable Architecture Design for Reverse Protocol Engineering
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor)A ZVS-resonant bifilar drive circuit for SRM with a reduction in stress voltage of switches
, Article International Aegean Conference on Electrical Machines and Power Electronics, ACEMP 2011 and Electromotion 2011 Joint Conference, Istanbul ; 2013 , Pages 125-128 ; 9781467350037 (ISBN) ; Najmi, V ; Ebrahimi, S ; Oraee, H ; Sharif University of Technology
2013
Abstract
Switched Reluctance Motors (SRMs) are widely used in high-speed and low voltage applications because of their attractive features such as robustness and simplicity. No winding on the rotor of this type of motors allows reaching high speed which is desired for many applications. Drive circuits of SRMs also play an important role in their performance and operation. In this paper, a new bifilar drive circuit for this type of motors has been proposed. This novel configuration has been tested and investigated by PSIM software. Results show that the new bifilar drive circuit highly reduces the voltage stresses on semiconductor switches, and also considerably reduces the switching losses which are...
A production bounce-back approach in the Cloud manufacturing network: case study of COVID-19 pandemic
, Article International Journal of Management Science and Engineering Management ; Volume 18, Issue 4 , 2023 , Pages 305-317 ; 17509653 (ISSN) ; Kazemisaboor, A ; Khaleghparast, S ; Fatahi Valilai, O ; Sharif University of Technology
Taylor and Francis Ltd
2023
Abstract
Industry 4.0 paradigm has enabled manufacturing systems with reformations for Cloud-based manufacturing business models. This reformation can create resilient structures as an inevitable opportunity for manufacturing supply networks. This is achieved by using service composition capabilities in Cloud manufacturing network which significantly enhances supply network performance when encountering disruptions. Focusing on redundancy as one of the most effective approaches to resiliency, a new model for manufacturing service composition is proposed. The model considers a minimum level of subentropy when responding to the demands at the process level while controlling the entropy overall at...
A Model of Risk Analysis for Iran Petroleum Contracts (IPC)
, M.Sc. Thesis Sharif University of Technology ; Haji, Alireza (Supervisor) ; Ayatollahi, Shahab (Supervisor)
Abstract
The economic framework of the petroleum sector exhibits significant divergence from other businesses owing to the substantial risks and uncertainties inherent in oil and gas ventures, compounded by highly unpredictable price fluctuations. Moreover, the abundance of uncertainties in the data employed for investment decisions in petroleum projects is very large, thus exerting a significant impact on the decision-making processes. This research delves into the impact of diverse risk factors on oil contracts and scrutinizes their influence on contractual dynamics. The study unfolds in three segments, encompassing an examination of economic factors shaping oil contracts, model design, and the...
Development of a One-Dimensional Compositional Simulator to Account for the Effects of Different Relative Permeability Models in Gas Condensate Reservoirs
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Gerami, Shahab (Co-Advisor)
Abstract
As the published statistics of prestigious international institutes show, the share of natural gas from the energy basket of the world is rising. This increase is due to some reasons such as decrease in oil reserves, discovery of new gas fields, lower environmental problems, etc. The Islamic Republic of Iran is not an exception of this rule; but also because of huge gas reservoirs that Iran has, it becomes very important for the Iranian government. Hence, research for predicting the behavior of such reservoirs is a necessary need of oil and gas industry.Both thermodynamic and flow behavior of gas condensate fluids are more complicated than other reservoir fluids. Its complex thermodynamic...
Modern Production Data Analysis of Bottom Water Drive Reservoir
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Gerami, Shahab (Supervisor)
Abstract
Hydrocarbon reservoirs may be classified on the basis of their drive mechanisms. In the reservoirs adjoined by water aquifers, waterdrive may be the primary production mechanism. The invasion of reservoir rock by aquifer water may have a significant impact on reservoir performance. Therefore, water influx into hydrocarbon reservoirs must be predicted accurately as a function of time, pressure history at the reservoir/aquifer interface, reservoir/aquifer size ratio, and aquifer characteristics.To forecast the performance in a waterdrive reservoir, an aquifer model simulating the fluid flow in the aquifer and flow from the aquifer into the reservoir is needed. Robust techniques for analysis of...
Investigation on Aplicability of Decline Curve Analysis for Gas Condensate Reservoirs
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Gerami, Shahab (Supervisor)
Abstract
Part 1: Techniques of production data analysis for single-phase oil and gas reservoirs have advanced significantly over the past few years. These techniques range from traditional (Arps and Fetkovich) to modern (they account for the variation of operating conditions at the wellbore). Although the production data analysis methods are used generally for single phase reservoirs, the application of these techniques for analysis of production data of a gas condensate reservoir may not yield the reliable answer due to the fact that the flow of fluid in gas condensate reservoirs is not single-phase. This study presents the treatment of the modern methods of production data analysis (single phase...
Experimental Investigation to Determine the Main Parameters for Viscoelastic Surfactant (VES) Injection for Acid Diversion in Reservoirs and Improving Their Design Conditions
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahab (Supervisor) ; Bazargan, Mohammad (Co-Advisor)
Abstract
The success of matrix acid production operations and its proper efficiency is one of the main challenges for oil and gas companies. The heterogeneity of the reservoir formation (especially the permeability difference) in the area around the well due to the presence of different reservoir layers results in the non-uniform distribution of acid among them and adds acidizing challenges. In order to improve production conditions, stimulation fluid transfer to the low permeability layer, which is the main target of acidizing. In this study, a new generation of chemical diverter, called Viscoelastic Surfactant, has been used. These materials have two components of elastic and viscous behavior, and...
Coupling Flow and Geochemistry for Numerical Simulation of Low Salinity/Smart Waterflooding in Carbonates
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahab (Supervisor) ; Mahani, Hassan (Supervisor)
Abstract
Due to the decrease in oil reserves in the world, increasing population and the growing demands for oil consumption in the world, increasing the oil recovery from oil reservoirs has become more important. Increasing the amount of oil production efficiency by using low salinity water/modified salinity water has been highly appreciated during the last two decades. Low-salt water is a new method, due to its advantages such as low cost, simplicity of operation and low environmental hazards. It is believed that low salinity water can alter the rock wettability from a more oil-wetting state to a more water-wetting state. In order to be able to predict the performance of low salinity water...
Energy management of smart home considering residences' satisfaction and PHEV
, Article 2018 International Conference on Smart Energy Systems and Technologies, SEST 2018, 10 September 2018 through 12 September 2018 ; 2018 ; 9781538653265 (ISBN) ; Shokri Gazafroudi, A ; Corchado, J. M ; Ebrahimi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Regarding the increasing number of electrical devices in the smart homes that leads to increase in total electricity consumption and cost, it is essential to use energy management methods to reduce the electricity cost. However, this can cause resident's dissatisfaction. Hence, it is important to define a method in which cost and dissatisfaction be optimized simultaneously. Among different services, an electric vehicle is the one that can be used as an energy storage system, so it can reduce the daily cost despite of increasing the total energy consumption. In this paper, we study the effect of the EV on the cost and dissatisfaction in our proposed method. © 2018 IEEE
Measured impact of different back-off points and cooling methods on pulse-to-pulse stability and sidelobe level of a high-power solid-state amplifier
, Article IET Radar, Sonar and Navigation ; Volume 14, Issue 2 , 2020 , Pages 335-340 ; Khodarahmi, E ; Ebrahimi, E ; Ahmadi, B ; Jalali, M ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
Using solid-state power amplifiers for next generation of weather radars becomes feasible by pulse compression techniques. In this study a 1.5 kW solid-state power amplifier (transmitter) for C-band weather radars is designed and fabricated by GaN high electron mobility transistor (HEMT) technology. An experimental setup based on heterodyne receiver with 16-bit digitiser is developed to investigate the behavior of the power amplifier under different cooling methods and back-off points. Several measurements with shaped LFM pulse show an approximately identical pulse to pulse (P2P) stability for 3 dB compression, P1dB and 2 dB back-off points while the best sidelobe level (SLL) is achieved for...
Probabilistic safety assessment of a UF 6 production process
, Article Advances in Safety, Reliability and Risk Management - Proceedings of the European Safety and Reliability Conference, ESREL 2011 ; 2012 , Pages 1384-1389 ; 9780415683791 (ISBN) ; Sharif University of Technology
2012
Abstract
Application of Probabilistic Safety Assessment (PSA) to a Uranium hexafluoride (UF 6) production process is presented in this paper. The process is constituted from three main units: UF 4 conversion to UF 6, condensation of produced UF 6 gas and tail gas treatment. Radioactive gas is present in all parts of the process and occurrence of high pressure or high temperature in the process equipments may lead to radioactive release to workplace and environment. The work is mainly based on PSA experience in nuclear power plants. Accordingly for the process, eight group of Initiating Events (IE) that lead to UF 6 gas release have been identified using HAZOP study. For each IE, based on related...
On the temperature control in self-controlling hyperthermia therapy
, Article Journal of Magnetism and Magnetic Materials ; Volume 416 , 2016 , Pages 134-140 ; 03048853 (ISSN) ; Sharif University of Technology
Elsevier
2016
Abstract
In self-controlling hyperthermia therapy, once the desired temperature is reached, the heat generation ceases and overheating is prevented. In order to design a system that generates sufficient heat without thermal ablation of surrounding healthy tissue, a good understanding of temperature distribution and its change with time is imperative. This study is conducted to extend our understanding about the heat generation and transfer, temperature distribution and temperature rise pattern in the tumor and surrounding tissue during self-controlling magnetic hyperthermia. A model consisting of two concentric spheres that represents the tumor and its surrounding tissue is considered and temperature...
Atmospheric icing effects of S816 airfoil on a 600 kW wind turbine's performance
, Article Scientia Iranica ; Volume 25, Issue 5B , 2018 , Pages 2693-2705 ; 10263098 (ISSN) ; Sharif University of Technology
Sharif University of Technology
2018
Abstract
This study investigates the aerodynamic loads and energy losses of a typical 600 kW wind turbine with S816 airfoil blade under two different icing conditions. Three sections at different radial positions were considered to estimate the icing effect along the blade. Ice accretion simulations in wet and dry regimes were carried out using the NASA LEWICE 3.2 computer program. The airflow simulations were performed with CFD method and SST k -ω turbulence model. The results of these simulations, including streamlines, surface pressure, skin friction, lift, and drag coefficients, were inspected for both clean and iced airfoils. In the case of wet iced airfoil, a separation bubble was created in...
Investigation on the Effects of the Polyacrylamide Copolymers and Their Blends with Sulfonated Lignin on the Soil Stabilization
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor) ; Ebrahimi, Hossein (Co-Supervisor)
Abstract
In recent years, dust pollution has become a worldwide issue due to the creation of serious environmental problems and the effects it has on human health. In this research, an environmentally friendly soil stabilizer has been synthesized, and its performance has been investigated. Acrylamide monomers were grafted onto sodium lignosulfonate chains, utilizing solution polymerization. The soil of the Ahvaz deserts was used in the analyses. Using EDX and DLS analyses, the components of this soil and the particle size distribution of the used soil were obtained. Characterization of the functional groups and the structure of the graft copolymer were done by FTIR and H-NMR analysis, respectively,...
Investigating Asphaltene Biodegradability by Microorganism Considering Oil-Water Interface
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahab (Supervisor) ; Taghikhani, Vahid (Supervisor)
Abstract
Asphaltine particle precipitation may lead to serious problems in petroleum industry; including wellbore transmissibility reduction. One of the proposed remedial methods is to make a use of the microorganisms which are able to consume the heavy hydrocarbon chains.
Hydrophobicity of a cell surface is one of the parameters which greatly affect the microorganism adhesion to water insoluble hydrocarbons, in which results a higher hydrocarbon biodegradation. Consequently as the hydrophobicity of a cell surface increases; the microorganism tendency to bond with the hydrocarbon molecule enhances. The presence of a surface active agent, as an instance a chemical surfactant, will affect the...
Hydrophobicity of a cell surface is one of the parameters which greatly affect the microorganism adhesion to water insoluble hydrocarbons, in which results a higher hydrocarbon biodegradation. Consequently as the hydrophobicity of a cell surface increases; the microorganism tendency to bond with the hydrocarbon molecule enhances. The presence of a surface active agent, as an instance a chemical surfactant, will affect the...
Assisted History-Matching for Fractured Reservoir Characterization
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahab (Supervisor) ; Masihi, Mohsen (Supervisor)
Abstract
Fracture reservoirs are highly heterogeneous. This heterogeneity makes the process of adjusting model parameters to match both the static geological and dynamic production data challenging. For this reason, the characterization of the fracture network of these reservoirs, which is achieved by finding the appropriate probability distributions of the fracture properties in the discrete fracture network model, requires the use of an integrated workflow for the process of history-matching.This thesis, presents an integrated workflow for the process of history-matching of naturally fractured reservoirs with field-scale performance capability. In this methodology, first, multiple discrete fracture...
Pore Scale Modeling of Fluid-Fluid Intercations During Low Salinity Waterflooding
, M.Sc. Thesis Sharif University of Technology ; Ayatollahi, Shahab (Supervisor) ; Mahani, Hassan (Supervisor)
Abstract
Recent studies have shown that the injection of low-salinity water would enhance the oil recovery factor for both the core scale and the field test. The evidence obtained from laboratory studies showed that the control of salinity and the composition of injected water has successfully affected the oil release, hence enhancing the oil recovery efficiency. In this method, by changing the type and amount of dissolved ions in the injected water, the water/oil/rock interactions are altered. Based on this, extensive studies have been focused on the mechanisms for the trapped oil release at the pore scale. Several mechanisms have been proposed to explain this phenomenon, which can be divided...
Recent studies have shown that the injection of low-salinity water would enhance the oil recovery factor for both the core scale and the field test. The evidence obtained from laboratory studies showed that the control of salinity and the composition of injected water has successfully affected the oil release, hence enhancing the oil recovery efficiency. In this method, by changing the type and amount of dissolved ions in the injected water, the water/oil/rock interactions are altered. Based on this, extensive studies have been focused on the mechanisms for the trapped oil release at the pore scale. Several mechanisms have been proposed to explain this phenomenon, which can be divided...
Impacts of using a social robot to teach music to children with low-functioning autism
, Article Paladyn ; Volume 12, Issue 1 , 2021 , Pages 256-275 ; 20814836 (ISSN) ; Shariati, A ; Heidari, R ; Shahab, M ; Alemi, M ; Meghdari, A ; Sharif University of Technology
De Gruyter Open Ltd
2021
Abstract
This article endeavors to present the impact of conducting robot-assisted music-based intervention sessions for children with low-functioning (LF) autism. To this end, a drum/xylophone playing robot is used to teach basic concepts of how to play the instruments to four participants with LF autism during nine educational sessions. The main findings of this study are compared to similar studies conducted with children with high-functioning autism. Our main findings indicated that the stereotyped behaviors of all the subjects decreased during the course of the program with an approximate large Cohen’s d effect size. Moreover, the children showed some improvement in imitation, joint attention,...