Improving performance of a station and smoothin the exit rate in an assembly line

, Article 2007 IEEE International Conference on Industrial Engineering and Engineering Management, IEEM 2007, 2 December 2007 through 4 December 2007 ; January , 2007 , Pages 1833-1837 ; 1424415292 (ISBN); 9781424415298 (ISBN) Elmi, A ; Nazabadi, M ; Sharif University of Technology

2007

Abstract

Assembly line is the most well-known mass production system which was first used by Henry Ford in automobile industries. Malfunction of a station will have an impact on the whole assembly line. Having a great impact on the performance of the whole assembly line, Interaction of the stations on each other should be considered precisely. In this paper we will use discrete event simulation to improve performance of a station and the whole assembly line by smoothing the exit rate, which is the entrance rate to the next station. At the end of this article, the results for a case problem are illustrated and several conclusions are driven. © 2007 IEEE

Dynamic Optimization Model for Electric Vehcile Routing in Ridesharing

, M.Sc. Thesis Sharif University of Technology Elmi, Amir (Author) ; Shafahi, Yousef (Supervisor)

Abstract

In the past few decades, a considerable number of researches is devoted to study different challenges of ridesharing systems. Thus, this paper presents a mathematical optimization model to find the exact solution of the dynamic dial-a-ride problem with a fleet of electric autonomous vehicles and charging stations. Furthermore, time windows at which model strives to serve trip requests, are defined over origin and destination of passengers. Contrary to many previous works, charging behavior of vehicle battery at charging station is modeled to follow the actual nonlinear function in real world. In addition, vehicles are able to charge the battery whether fully or partially, whichever is more...

Introducing a new cooling system based on the combined use of microchannel heat sinks and pulsating heat pipes

, Article Applied Thermal Engineering ; Volume 232 , 2023 ; 13594311 (ISSN) Ahmadian Elmi, M ; Hajmohammadi, M. R ; Nourazar, S ; Vafai, K ; Shafii, M. B ; Sharif University of Technology

Elsevier Ltd 2023

Abstract

In this research, a novel cooling system based on the combined use of a microchannel heat sink and pulsating heat pipes has been introduced. The pulsating heat pipe is considered a part of the microchannel heat sink structure, and it is the first time that these two systems have been studied simultaneously. Pulsating heat pipe has been modeled in a three-dimensional form in the wall of the microchannel heat sink, and the two-phase volume of fluid (VOF) model was used for numerical modeling. The effect of the physical and geometrical parameters of the pulsating heat pipe, such as the filling ratio and the number of loops, on the thermal performance of the microchannel heat sink has been...

Design and Optimization of Solar Hydrogen Production System Based on Photoelectrochemical Cell Model

, M.Sc. Thesis Sharif University of Technology Elmi, Mohammad (Author) ; Ghahnavieh, Rajabi (Supervisor) ; Moshfegh, Alireza (Supervisor) ; Naseri, Naimeh (Co-Supervisor)

Abstract

The optimized geometry and structure of iron oxide(Fe2O3) nanorod arrays as the photoanodes of photoelectrochemical cells have been calculated. Using finite element method, different structures have been studied in order to maximize the photocurrent density generated by the photoanodes. Two main characteristics of nanorod arrays namely the aspect ratio of nanorod and the density of nanorods in array have been selected as the variables. The absorbance of the photoanode has been calculated using Electromagnetic Waves Physics in COMSOL Multiphysics software. In this study, nanorods with aspect ratio of 3.6 to 40 have been varied and compared. The results reveal that the current density has a...

Analysis of gene expression profiles and protein-protein interaction networks in multiple tissues of systemic sclerosis

, Article BMC Medical Genomics ; Volume 12, Issue 1 , 2019 ; 17558794 (ISSN) Karimizadeh, E ; Sharifi Zarchi, A ; Nikaein, H ; Salehi, S ; Salamatian, B ; Elmi, N ; Gharibdoost, F ; Mahmoudi, M ; Sharif University of Technology

BioMed Central Ltd 2019

Abstract

Background: Systemic sclerosis (SSc), a multi-organ disorder, is characterized by vascular abnormalities, dysregulation of the immune system, and fibrosis. The mechanisms underlying tissue pathology in SSc have not been entirely understood. This study intended to investigate the common and tissue-specific pathways involved in different tissues of SSc patients. Methods: An integrative gene expression analysis of ten independent microarray datasets of three tissues was conducted to identify differentially expressed genes (DEGs). DEGs were mapped to the search tool for retrieval of interacting genes (STRING) to acquire protein-protein interaction (PPI) networks. Then, functional clusters in PPI...

Stimulus-responsive sequential release systems for drug and gene delivery

, Article Nano Today ; Volume 34 , 2020 Ahmadi, S ; Rabiee, N ; Bagherzadeh, M ; Elmi, F ; Fatahi, Y ; Farjadian, F ; Baheiraei, N ; Nasseri, B ; Rabiee, M ; Tavakoli Dastjerd, N ; Valibeik, A ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology

Elsevier B.V 2020

Abstract

In recent years, a range of studies have been conducted with the aim to design and characterize delivery systems that are able to release multiple therapeutic agents in controlled and programmed temporal sequences, or with spatial resolution inside the body. This sequential release occurs in response to different stimuli, including changes in pH, redox potential, enzyme activity, temperature gradients, light irradiation, and by applying external magnetic and electrical fields. Sequential release (SR)-based delivery systems, are often based on a range of different micro- or nanocarriers and may offer a silver bullet in the battle against various diseases, such as cancer. Their distinctive...

Construction of an Experimental Device for Foaming Agent and an Experimental Study of the Properties of Foaming Agent

, M.Sc. Thesis Sharif University of Technology Mohammad Karami (Author) ; Bazargan, Mohammad (Supervisor)

Abstract

The primary purpose of acidizing operations in the oil and gas industry is to enhance hydrocarbon production. Acidizing has been a common and conventional method for years, especially when production engineers face issues like declining reservoir pressure leading to reduced production rates. Initially, the treatment solution is referred to as matrix acidizing. In acidizing operations, different additives are combined with the acid to control its behavior in the reservoir. These additives may include iron control agents, corrosion inhibitors, friction reducers, and more. Incompatibility among these additives, the acid, and reservoir fluids can lead to severe damage to the reservoir....

Numerical Analysis of An Annular Gas Turbine Combustor

, M.Sc. Thesis Sharif University of Technology Gandomi, Mohammad Hossein (Author) ; Farshchi, Mohammad (Supervisor)

Abstract

The goal of this research is the simulation of the annular combustion chamber of the turbine engine utilized by liquid fuel. The achievement to this goal will lead to create numerical tools for parametric study, analysis and combustion chamber designing.For this reason simple geometry has been considered. This simplicity of geometry causes to facilitate in parametric study and decrease in saving time for modeling and meshing. This combustion chamber is a simplified model of engine CF6. In recent study, the k – ε realizable model has been used for turbulence modeling. For non-adiabatic condition, chemical reaction is dissolved by utilizing probability density function along with laminar...

A misbehavior‐tolerant multipath routing protocol for wireless Ad hoc networks [electronic resource]

, Article International Journal of Research in Wireless Systems (IJRWS) ; Vol. 2, Issue 9, pp. , Sep. 2013 Sedghi, H. (Haniyeh) ; Pakravan, Mohammad Reza ; Aref, Mohammad Reza ; Sharif University of Technology

Abstract

Secure routing is a major key to service maintenance in ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. As a result of the resource limitations in such networks nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a novel data redirection method to mitigate the impact of node misbehavior on network...

Theoretical and Experimental Study to Conversion of AUC to UO2 by Microwave Heating

, Ph.D. Dissertation Sharif University of Technology Labbaf, Mohammad Hossein (Author) ; Otukesh, Mohammad (Supervisor) ; Ghannadi Maragheh, Mohammad (Co-Advisor) ; Ghasemi, Mohammad Reza (Co-Advisor)

SAR Imaging Using the TomoSAR Technique to Resolve Multiple Scatterers

, M.Sc. Thesis Sharif University of Technology Omati, Mohammad Mahdi (Author) ; Bastani, Mohammad Hassan (Supervisor) ; Karbasi, Mohammad (Co-Supervisor)

Abstract

During the last few years, the study of urban environment structures is considered as a research field of interest in remote sensing. In satellite observations of the earth's surface, continuous imaging in terms of time and space has caused the remote sensing technique to be proposed as a useful and efficient tool for the analysis of urban areas. Obtaining quantitative spatial information from the urban environment in fields such as determining the height of buildings plays an essential role in urban planning, monitoring damage to buildings, establishing communication bases and digital cities. During the last two decades, the use of Tomosar approach in order to reconstruct the structures of...

Estimating Possible Effects of Subsidies in Competition and Development of Fixed Broadband Internet

, M.Sc. Thesis Sharif University of Technology Mohammadi, Mohammad Ali (Author) ; Vesal, Mohammad (Supervisor) ; Rahmati, Mohammad Hossein (Supervisor)

Abstract

In this work, the dynamic competition between firms providing internet services is studied. The framework is Markov equilibrium whereby structural parameters are obtained using two-step estimations, allowing for analyzing the situation in case of subsidies for service upgrade. The results show that such subsidy has little effect on the number of firms while increasing the number of fast firms

Estimating Price Elasticity of Natural Gas Demand in Iran's Residential Sector: A Regression Discontinuity Approach

, M.Sc. Thesis Sharif University of Technology Makhsousi, Mohammad Hossein (Author) ; Rahmati, Mohammad Hossein (Supervisor) ; Vesal, Mohammad (Supervisor)

Abstract

Estimating the price elasticity of gas demand involves complexities depending on the gas market structure and pricing mechanisms in different countries. Distinguishing between supply and demand shocks and block pricing are among the main challenges that can cause endogeneity in elasticity estimates. Iran's domestic gas network, one of the largest and most extensive household gas markets, is divided into five climatic zones based on weather conditions. The pricing steps for these five climates during the five cold months are such that a customer in a warmer climate pays higher prices. Conversely, the pricing steps for the seven warm months are the same for all climates. This policy creates a...

Estimate the Effect of Religiosity on Voter Turnout

, M.Sc. Thesis Sharif University of Technology Jarrahi, Mohammad Mahdi (Author) ; Rahmati, Mohammad Hossein (Supervisor) ; Vesal, Mohammad (Supervisor)

Abstract

The correlation between religious adherence and voter turnout is widely studied. However, whether the relation is causal is an open question. We use Household Expenditures and Income Survey (HEIS) data in Iran, which encompasses nine distinct religious expenditures. These expenditures have low correlation with each other and represent different aspects of religious adherence. We use Imamzadeh (some historical holy shrines) as Instruments to estimate the causal effect of religious expenditures on voter turnout. The results reveal that religious expenditures influence both presidential and parliamentary voter turnout, with a notably stronger impact on presidential elections

Joint Optimization of Computation Offloading and Resource Allocation in Mobile Edge Computing Networks

, M.Sc. Thesis Sharif University of Technology Shokouhi, Mohammad Hossein (Author) ; Pakravan, Mohammad Reza (Supervisor) ; Hadi, Mohammad (Co-Supervisor)

Abstract

Mobile edge computing (MEC) is a promising technology that aims to resolve cloud computing’s issues by deploying computation resources at the edge of mobile network and in the proximity of users. The advantages of MEC include reduced latency, energy consumption, and load on access and mobile core networks, to name but a few. Despite all the aforementioned advantages, the mobility of mobile network users causes the traditional MEC architecture to suffer from several issues, such as decreased efficiency and frequent service interruption. One of the methods to manage users’ mobility is virtual machine (VM) migration, where the VM containing the user’s task is migrated to somewhere closer to...

Non-Scratch, Antibacterial And Self-cleaning SiO2/TiO2 Nano Composite Coating on Surgical Tools By Sol-Gel

, M.Sc. Thesis Sharif University of Technology Ahmadi, Mohammad Hossein (Author) ; Ghorbani, Mohammad (Supervisor)

Abstract

In this study TiO2/SiO2 thin films were prepared by sol-gel method from Tetra isopropylortho Titanate(TIPT) as the principle of TiO2 material with Tera ethoxysilane(TEOS) as the principle of SiO2 material to achieve high scratch-resistant , antibacterial and self-cleaning surface area under the effect of various percentage of SiO2 . Film deposition was carried out using a dip-coating technique and heat-treatment was used at 700ºC to achieve crystalline of films with excellent adherence the of substrate.
The surface morphology of the films has been observed by Scanning Electron Microscope (SEM) and the tribological properties of the surface were investigated by Atomic Force Microscope...

Simulation and Control of an Aromatic Extractive Distillation Column

, M.Sc. Thesis Sharif University of Technology Karima, Mohammad Mahdi (Author) ; Shahrokhi, Mohammad (Supervisor)

Abstract

In this study steady state and dynamic simulation of an NFM extractive distillation unit for seperation of aromatics and non-aromatic components has been carried out. Column output composition obtained with experimental binary coefficients is compared with those obtainded by UNIFAC equation. The results indicate that using UNIFAC for all binrary coefficients results in an unacceptable error in concentration of benzene. If the experimental binary coefficents of benzene with NFM are used and the rest are calculated by UNIFAC equation, the simulation results will be very close to those obtained via experimental binary coefficients. Also it is shown that considering a constant efficiency for all...

Investigation the Effects of Parking Pricing and Improving Public Transportation Policies on Private Car Use Reduction in Central Business District

, M.Sc. Thesis Sharif University of Technology Salavati, Mohammad Ali (Author) ; Kermanshah, Mohammad (Supervisor)

Abstract

Nowadays, with population growth and vehicle traffic increase, only providing transportation supply couldn’t answer the transportation demand. One of the most important solutions to reduce traffic is transportation demand management (TDM). In this research, the effects of parking pricing and improving public transportation services on private car demand reduction in city center are examined. The data are collected from private cars users in the city center of Isfahan through interviews. By stated preference method, the impacts of parking price and public transit travel time and other related factors were investigated. For this purpose, binary logit, multinomial logit and nested logit models...

Iran’s Air Quality Modeling Using CMAQ-WRF Coupled Model

, M.Sc. Thesis Sharif University of Technology Mohegh, Mohammad Hassan (Author) ; Arhami, Mohammad (Supervisor)

Abstract

Industrialization has brought about air pollution which is one of the most important factors threatening human health. The most efficient method to improve air quality include preventing the emission of pollutants by making laws and regulations. In order to set appropriate regulations, there needs to be a correct understanding of the problem. The purpose of this research is to identify such factors and create a correct understnding of the problem in Iran by constructing a Model of Iranian air qulity. The model used in this research, CMAQ is one of the most comprehensive and state of the art models in transport of pollutnts and chemical reactions in the atmosphere. The inputs into CMAQ...

H.264 Decoder for Portable Application

, M.Sc. Thesis Sharif University of Technology Alizadeh, Mohammad Sadegh (Author) ; Sharifkhani, Mohammad (Supervisor)

Abstract

As mobile multimedia services become popular, it is expected that mobile devices provide more multimedia functions such as real-time video playback, TV watching, and video games. However, real-time video applications running on mobile devices are heavily constrained by their limited computing power, compared to high-end consumer devices. In order to playback a high resolution video on mobile devices, a typical approach would be to fully decode video bitstream into the pixel-domain, and then spatially downscale the decoded frames at a desired resolution. However, due to large computation and memory required for decoding followed by downscaling, this approach is unsuitable for real-time video...