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paydar-zarnaghi--mahnaz
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An Efficient Decision Making Model for Reducing the Rate of Crashes in Accidents in Iran
, M.Sc. Thesis Sharif University of Technology ; Kourosh, Eshghi (Supervisor)
Abstract
Today the losses due to road accidents in Iran are very high. For this reason, it is essential to investigate the effective factors on the road accidents. Therefore, at first, there is a need to identify the solutions of reducing the accidents, their priories and finally their efficiency improvement. In this research, using Hierarchical Analysis Method, the solutions to reduce the accidents are prioritized and then In order to conduct the AHP analysis, Expert Choice software was chosen. According to research findings, the factors that lead to accidents are categorized as: Human factors, road environmental factors, vehicle, natural factors and managerial factors. The findings show that in...
Production of drug Loaded Microgels Using Microfluidic
, M.Sc. Thesis Sharif University of Technology ; Saadatmand, Maryam (Supervisor) ; Eskandari, Mahnaz (Supervisor)
Abstract
Microfluidic systems have the ability to produce microgels with uniform size distribution and spherical shape due to the laminar flow and better control of the flow rates. Spherical microgels with same size can be used as high-potential carriers for drug release. An important challenge in the production of these drug-carrying microgels is the simultaneous process of drug loading into microgels and their production. The overall goal of this project was to produce drug-carrying microgels with uniform size distribution that show controlled drug release. To achieve this goal, various factors such as the type of polymer, the type of drug, the volume ratio of the polymer and the drug and the...
Influence of fines content and type on the small-strain shear modulus of sand
, Article Scientia Iranica ; Vol. 21, issue. 4 , 2014 , p. 1281-1296 ; Ahmadi, M. M ; Sharif University of Technology
2014
Abstract
The small-strain shear modulus, Go, is an important fundamental soil property. Although many studies have been conducted on this property for clean sands and pure clays, small-strain behavior for mixtures of sand and fines has been less addressed. This paper presents the results of a comprehensive laboratory study on G0 value of sand containing various amounts of different fines. To this aim, bender elements were integrated into a conventional triaxial apparatus, and shear wave velocity was measured on samples of sand with different amounts of highly-plastic, medium-plastic, low-plastic, or non-plastic fines at different void ratios. Measuring the shear wave velocity and thus...
Requirements for soil-specific correlation between shear wave velocity and liquefaction resistance of sands
, Article Soil Dynamics and Earthquake Engineering ; Vol. 57, issue , 2014 , pp. 152-163 ; ISSN: 02677261 ; Akbari Paydar, N ; Sharif University of Technology
2014
Abstract
The application of the simplified method for evaluating the liquefaction potential based on shear wave velocity measurements has increased substantially due to its advantages, especially for microzonation of liquefaction potential. In the simplified method, a curve is proposed to correlate the cyclic resistance ratio (CRR) with overburden stress-corrected shear wave velocity (Vs1). However, the uniqueness of this curve for all types of soils is questionable. The objective of this research is to study whether the correlation between CRR and Vs1 is unique or not. Besides, the necessity of developing the soil-specific correlations is also investigated. Based on laboratory test data, a new...
Correlation of shear wave velocity with liquefaction resistance for silty sand based on laboratory study
, Article 15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability, 9 November 2015 through 13 November 2015 ; 2015 , Pages 794-799 ; Ahmadi, M. M ; Sharif University of Technology
Asian Regional Conference on Soil Mechanics and Geotechnical Engineering
2015
Abstract
Several methods have been used for the evaluation of liquefaction potential, among which the simplified method is mostly used. In this method, which is mainly based on standard penetration test (SPT), cone penetration test (CPT) and shear wave velocity (Vs) measurement, a boundary curve is provided to separate the liquefiable and non-liquefiable soil zones. Vs measurement is a good alternative method of penetration-based methods (SPT and CPT). This is especially true in micro-zonation of liquefaction potential. Although relatively large studies have been carried out to establish the correlation between Vs and liquefaction resistance for sands; there are uncertainties about the effects of...
Effect of fines type and content of sand on correlation between shear wave velocity and liquefaction resistance
, Article Geotechnical and Geological Engineering ; 2016 , Pages 1-20 ; 09603182 (ISSN) ; Ahmadi, M. M ; Sharif University of Technology
Springer International Publishing
2016
Abstract
The use of shear wave velocity (Vs) measurements as an in situ test for evaluation of liquefaction potential has increased substantially due to its advantages. Relatively large numbers of studies have been performed to establish the correlation between Vs and liquefaction resistance (CRR) of clean sands. Usually, natural sands contain silt and/or clay, and previous studies have shown that both the amount of fines and their nature influence the values of CRR as well as Vs. Therefore, the CRR–Vs correlations may also be affected by fines content and type of sandy soils. However, effect of fines content and especially fines type of sandy soils on the correlation between Vs and CRR is...
Anodizing behavior and electrochemical evaluation of accumulative roll bonded Al and Al-SiC composite
, Article Surface and Coatings Technology ; Volume 408 , 2021 ; 02578972 (ISSN) ; Alishavandi, M ; Paydar, M. H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Accumulative roll bonded (ARBed) AA1050 and Al-2 vol% SiCp (AMC) samples were anodized in an H2SO4 electrolyte to improve corrosion resistance. The SEM images revealed that the anodic oxide's morphology is significantly dependent on the microstructure of the ARBed bare samples, owing to high internal energy that accelerates Al consumption during anodizing process. Potentiodynamic polarization measurements and EIS evaluation showed that anodic oxide improves the corrosion resistance of both ARBed AA and AMC samples; however, the electrochemical behavior of the processed samples changed due to the formation of a complex oxide structure comprising of twisted pore channels and attack routes. ©...
The Effect of Fines Content and its Type on Shear Wave Velocity and Liquefaction Resistance of Sandy Soils
, Ph.D. Dissertation Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor)
Abstract
Liquefaction is one of the most destructive geotechnical phenomena, and so the determination of soil liquefaction is very important. Shear wave velocity measurement is one of the methods of the soil liquefaction potential evaluation. The use of this method has increased substantially in recent years, due to its advantages compared to other methods, especially for microzonation of liquefaction potential. However, proposed curves for liquefaction evaluation which are based on the shear wave velocity measurement are more conservative than curves based on SPT and CPT, especially for sands containing fines. Local information from sites that have been liquefied previously and the shear wave...
Design and Fabrication of Microfluidic System to Produce Microgel for Drug Delivery Application
, M.Sc. Thesis Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Saadatmand, Maryam (Supervisor) ; Eskandari, Mahnaz (Supervisor)
Abstract
Due to the increasing need of use of drugs and insufficient efficiency of conventional methods, drug delivery systems has gathered a lot of interests. There are different systems existing for controlled drug delivery, among which is implementation of hydrogel microparticles (microgels) as carriers with high potential. The most important factor in these systems is size distribution of drug-carrying microgels and a narrow size distribution leads to a controlled and suitable release. Due to unique characteristics of microfluidic systems, significant focus has been placed on them nowadays for production of microgels with suitable morphology and narrow size distribution. Therefore, in this study...
Influence of autogenous seeding on densification and microstructure in processing of γ-alumina nanopowders
, Article Phase Transitions ; Volume 84, Issue 1 , 2011 , Pages 1-14 ; 01411594 (ISSN) ; Maleksaeedi, S ; Paydar, M. H ; Saadat, S ; Sharif University of Technology
2011
Abstract
The effect of α-Al 2O 3 seeds and MgO on the densification behavior and microstructure of the nanocrystalline γ-Al 2O 3 powder was investigated. The required α-Al 2O 3 seeds were produced by 'autogenous seeding' where the seeds were obtained by calcination of the initial nanosized γ-Al 2O 3 powders above its transformation temperature and incorporated into γ-Al 2O 3 matrix. The seeds were characterized by means of laser particle size analyzer, X-ray diffraction, and Brunauer-Emmett-Teller surface analyzer. The simultaneous influence of α-Al 2O 3 seeds and MgO on γ-Al 2O 3 behavior was evaluated by differential thermal analysis, densitometry, and electron microscopy. The results showed that...
Optimizing decentralized production–distribution planning problem in a multi-period supply chain network under uncertainty
, Article Journal of Industrial Engineering International ; Volume 14, Issue 2 , 2018 , Pages 367-382 ; 17355702 (ISSN) ; Mahdavi, I ; Mahdavi Amiri, N ; Paydar, M. M ; Sharif University of Technology
SpringerOpen
2018
Abstract
Decentralized supply chain management is found to be significantly relevant in today’s competitive markets. Production and distribution planning is posed as an important optimization problem in supply chain networks. Here, we propose a multi-period decentralized supply chain network model with uncertainty. The imprecision related to uncertain parameters like demand and price of the final product is appropriated with stochastic and fuzzy numbers. We provide mathematical formulation of the problem as a bi-level mixed integer linear programming model. Due to problem’s convolution, a structure to solve is developed that incorporates a novel heuristic algorithm based on Kth-best algorithm, fuzzy...
Optimizing decentralized production–distribution planning problem in a multi-period supply chain network under uncertainty
, Article Journal of Industrial Engineering International ; 2017 , Pages 1-16 ; 17355702 (ISSN) ; Mahdavi, I ; Mahdavi Amiri, N ; Paydar, M. M ; Sharif University of Technology
2017
Abstract
Decentralized supply chain management is found to be significantly relevant in today’s competitive markets. Production and distribution planning is posed as an important optimization problem in supply chain networks. Here, we propose a multi-period decentralized supply chain network model with uncertainty. The imprecision related to uncertain parameters like demand and price of the final product is appropriated with stochastic and fuzzy numbers. We provide mathematical formulation of the problem as a bi-level mixed integer linear programming model. Due to problem’s convolution, a structure to solve is developed that incorporates a novel heuristic algorithm based on Kth-best algorithm, fuzzy...
A multi-objective optimization model for dynamic virtual cellular manufacturing systems
, Article International Journal of Industrial Engineering and Production Research ; Volume 33, Issue 2 , 2022 ; 20084889 (ISSN) ; Mahdavi, I ; Mahdavi Amiri, N ; Paydar, M. M ; Sharif University of Technology
Iran University of Science and Technology
2022
Abstract
Companies and firms, nowadays, due to mounting competition and product diversity, seek to apply virtual cellular manufacturing systems to reduce production costs and improve quality of the products. In addition, as a result of rapid advancement of technology and the reduction of product life cycle, production systems have turned towards dynamic production environments. Dynamic cellular manufacturing environments examine multi-period planning horizon, with changing demands for the periods. A dynamic virtual cellular manufacturing system is a new production approach to help manufacturers for decision making. Here, due to variability of demand rates in different periods, which turns to flow...
Fabrication and Characterization of Anode Supported Micro-tubular Solid Oxide Fuel Cells Prepared by Successive Non-aqueous Electrophoretic Deposition
, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali (Supervisor) ; Paydar, Mohammad Hossein (Supervisor)
Abstract
The commercial breakthrough of micro-tubular solid oxide fuel cells (MT-SOFCs) is still facing so many challenges because of the complexity of their manufacturing process and the high cost associated with them. By deploying electrophoretic deposition as a simple and cost-effective method, the different components of the fuel cells (the anode, electrolyte, and cathode) can deposit on the graphite rod as a sacrificial substrate. The next step is eliminating the sacrificial substrate which will make hollow rods of cell components. The results of this study show that the use of a particular type of pencil lead will have a minimal negative impact on the overall fuel cell performance, leading to a...
Designing a dynamic buyer-supplier coordination model in electronic markets using stochastic petri nets
, Article International Journal of Information Systems and Supply Chain Management ; Volume 1, Issue 3 , 2008 , Pages 1-20 ; 19355726 (ISSN) ; Mohebbi, S ; Cho, N ; Paydar, M. M ; Mahdavi Amiri, N ; Sharif University of Technology
2008
Abstract
Functional relationship between supplier and buyer in an open market place leads to investigate the role of both quantifiable and non-quantifiable parameters in coordination mechanism with the aim of achieving higher performance in supply chain activities. Here, we develop a supply chain model and a new agent to analyze and simulate the players' behavior in the network. A cooperative game theory framework is utilized between buyer and supplier in order to increase the supply chain performance. The study is supported by presenting SC Net Optimizer as a tool for implementing the proposed coordination mechanism and evaluates the performance of the chain by simulation using stochastic Petri nets...