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alihosseini--amir-mohammad
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Integrated Maisotensko Cycle with Desiccant-Based Ejector Cooling System for Energy and Carbon Saving
, M.Sc. Thesis Sharif University of Technology ; Aavami, Akram (Supervisor)
Abstract
Due to the heat waves in the summers in recent years, the increase in temperature and climate changes, as well as the increase in population, the demand for cooling in the home is increasing day by day. This increase in demand has had a significant impact on the supply of electricity in Iran. The lack of capacity has caused more power outages to occur in the summer in recent years in Iran. To avoid these problems, the capacity of power plants can be increased, which causes more fuel consumption and environmental pollution. Another solution can be to reduce the energy consumption of subscribers. This solution not only reduces energy consumption, but also reduces environmental problems. ...
Equilibrium sorption of crude oil by expanded perlite using different adsorption isotherms at 298.15 k
, Article International Journal of Environmental Science and Technology ; Volume 7, Issue 3 , June , 2010 , Pages 591-598 ; 17351472 (ISSN) ; Taghikhani, V ; Safekordi, A. A ; Bastani, D ; Sharif University of Technology
2010
Abstract
During the past decades, a significant increase occurred in accidental oil spill in the aquatic environments. In this regard, oil spill in Marine freshwater is still considered as a major environmental hazard. In this research, the experimental data on the sorption capacity of expanded perlite to crude oil were correlated with the equilibrium isotherm of Langmuir, Freudlich, Tempkin and the three parameter Redlich-Peterson isotherms. The results obtained from each specified isotherms were compared and accuracy of the models were favorably discussed. Accuracy of each model using the error function were evaluated. Moreover, the effect of type of objective function on the final results was...
Study of oil sorption by expanded perlite at 298.15 K
, Article Separation and Purification Technology ; Volume 52, Issue 2 , 2006 , Pages 295-300 ; 13835866 (ISSN) ; Safekordi, A. A ; Alihosseini, A ; Taghikhani, V ; Sharif University of Technology
2006
Abstract
Sorption capacity as well as sorption kinetics of oil onto four different expanded perlites with different physical and surface properties were studied. In order to meticulously measure the amount of oil to be sorbed onto the adsorbents used in this study both static and dynamic methods were employed. It would be worth noting that the adsorbent, i.e., perlite can spread on the oil and float on the surface thanks to its low density. The variation of the amount of oil sorbed onto the adsorbents with time was recorded and the weight of adsorbent was monitored at each specified time. The experimental results showed that grain sizes with high surface area can sorb oil to be spread on water...
Driving Behavior Estimation with Smartphone Data
, M.Sc. Thesis Sharif University of Technology ; Samimi, Amir (Supervisor)
Abstract
Identifying driving behaviors and building an efficient and accurate driving behavior recognition model is of paramount importance for improving driving safety. Nowadays, with the ubiquity of smartphone sensors, many researchers are using smartphone sensory data to create models which forecast driving behaviors. This research introduces a logit model that predicts nine types of driving events using accelerometer and gyroscope sensors with an accuracy of 76 percent
Thermal Simulation of Sponge Iron Production by Höganäs Method
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
Sponge Iron production is conducted in various methods that one of them is using coal as a reduction agent. Hoganas process is a different coal-based method that has not been investigated in details. Therefore, the heat transfer method in the system is one of the basic steps to a better recognition of this process (with special Hoganas charging). The present paper investigates the temperature distribution method in the Hoganas cylinder through a numerical model using finite elements. The effects of different parameters, namely preheating and porosity were studied on ceramic crucible made from silicon carbide and it was observed that the consumption energy decreases with the increase of...
Consequence Modelling and Probabilistic Risk Assessment of Oil Spills in the Marine Waters
, Ph.D. Dissertation Sharif University of Technology ; Raie, Mohammad (Supervisor)
Abstract
Different causes in the exploration, production and transport of oil in the marine environment result in oil spill events. Since elimination of the probability of occurrence of spills is not possible, it is important to have a plan to control the risk of oil spills by optimal response. In this research, a general stucture is presented for the DSS required for oil spill response planning. This system can be used for evaluation of the effectiveness of response drills, and risk-based ranking of receptor areas and spill sources. Ranking based on risk is realized through probabilistic or stochastic risk assessment. The applicability of the proposed system is examined in differnet case studies in...
Producing ultrafine-grained aluminum rods by cyclic forward-backward extrusion: Study the microstructures and mechanical properties
, Article Materials Letters ; Volume 74 , May , 2012 , Pages 147-150 ; 0167577X (ISSN) ; Zaeem, M. A ; Dehghani, K ; Shivaee, H. A ; Sharif University of Technology
2012
Abstract
A cyclic forward-backward extrusion (CFBE) process was used as a severe plastic deformation (SPD) technique to produce ultrafine-grained aluminum rods. Yield strength and tensile strength of the specimens increased by increasing the number of CFBE cycles, while elongation to break decreased due to an increase in the grain refinement and microhardness. According to transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) results, the average grain size was reduced from 120 μm to 315 nm after only 3 cycles of CFBE
Investigating Effects of Urban Freight Companies' Scale on their Transport Efficiency and Developing a Tool for Integration of Freight Companies
, M.Sc. Thesis Sharif University of Technology ; Samimi, Amir (Supervisor) ; Kermanshah, Amir Hassan (Supervisor)
Abstract
In this research, a dashboard has been developed to support decision-making in the integration of freight companies. Freight companies usually consist of a limited number of vehicles due to the high cost of vehicles, while the fixed costs of a freight company constitute a significant part of that company's total cost. Therefore, if these companies are merged, their total cost will be substantially decreased. Moreover, under particular demand levels, the integration of freight companies reduces the mileage, travel time, and the number of required cars. Therefore, the integration of freight companies not only reduces fixed costs but also reduces other costs including greenhouse gas costs by...
Nanocrystallization kinetics and magnetic properties of the melt spun amorphous (Fe0.5Co0.5)77Si11B 9Cu0.6Nb2.4 alloy
, Article Thermochimica Acta ; Vol. 575, issue , 2014 , p. 64-69 ; Samadi, M ; Alihosseini, H ; Madaah Hosseini, H. R ; Sharif University of Technology
2014
Abstract
Kinetics of crystallization in an amorphous (Fe0.5Co 0.5)77Si11B9Cu0.6Nb 2.4 (at.%) alloy was investigated using differential scanning calorimetry (DSC). Transformed fraction as a function of temperature was obtained by accurate DSC measurement and the experimental data analyzed with Vyazovkin model-free kinetic method. Reconstructed form of the experimental kinetics model, g(α), clearly showed the crystallization mechanism do not belongs to a single model but almost follows the Avrami-Erofe'ev. Magnetic coercivity and hysteresis loss values of the annealed samples at 823 K were 7.5 A m-1 and 1.2 J m-3, compared to 17.1 A m-1 and 37.1 J m-3 for as spun samples. Magnetic measurements show the...
Climatic Map of Atmospheric Corrosion of Iran
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Atmospheric corrosion as one of the most principal factors of destruction is not Climatic map of atmospheric corrosion is closely related to air and atmospheric factors among which we can point out to different types of atmospheric pollutions such as NOX, SOX gases and pendant materials as well as the rate of humidity and rain and even the rate of sun radiation. The effects of these factors beside each other cause the speed of corrosion from a climate to another climate to be changed, which is presentable in form of a map. There is a 2 method to provide this map. First build up a station to measure the corrosion data and collect them in a long period of time. This method are time consuming...
Reconfigurable Architecture For Cryptanalysis Applications
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor)
Abstract
Nowadays, the significance of securing data and information is undeniable. Cryptography is being used to provide data security. In addition, cryptanalysis is required to evaluate the effectiveness of cryptography methods, and hence, it is an essential concept for securing data. In general, the cryptography functions shall be designed in a way to impose a high load of time-intensive operations to prevent an adversary from accessing the main data from the encrypted data. As a result, cryptography and cryptanalysis algorithms need high performance computations. So far, a number of methods have been proposed to support the required performance. These methods include: distributed computing and...
Regularization from the Machine Learning Point of View
, M.Sc. Thesis Sharif University of Technology ; Daneshgar, Amir (Supervisor)
Abstract
In traditional machine learning approaches to classification, one uses only a labeled set to train the classifier. Labeled instances however are often difficult, expensive, or time consuming to obtain, as they require the efforts of experienced human annotators. Meanwhile unlabeled data may be relatively easy to collect, but there has been few ways to use them. Semi-supervised learning addresses this problem by using large amount of unlabeled data, together with the labeled data, to build better classifiers. Because semi-supervised learning requires less human effort and gives higher accuracy.Formally, this intuition corresponds to estimating a label function f on the graph so that it...
On the Density Matrix of Graphs
, M.Sc. Thesis Sharif University of Technology ; Daneshgar, Amir (Supervisor)
Abstract
Density matrix of graphs as defined -for the first time- in [S. Braunstein and et al. The laplacian of a graph as a density matrix, Annals of Combinatorics, (2006)], is obtained through dividing the Laplacian matrix by the degree sum. This matrix is also semi-positive and trace one. Therefore one may talk about the Von Neumann entropy of this matrix. In [F. Passerini, S. Severini. Quantifying complexity in networks: The Von Neumann entropy. IJATS, (2009)], authors have claimed that this quantity can be consisered as a measure of regularity. Here, using a geometric interpretation of Von Neumann entropy, expresed in [G. Mitchison, R. Jozsa, Towards a geometrical interpretation of quantum...
Data-Oriented Verification of Programs
, M.Sc. Thesis Sharif University of Technology ; Ardeshir, Mohammad (Supervisor)
Abstract
The verification of programs is one of the most important subjects in Computer Science. In this thesis, after reviewing preliminary subjects, While-Programming computational model is presented and its semantics is discussed. Next, the axiomatic method of Hoare is presented, which is a deduction system for verification of programs. With the help of Hoare method, the idea of Data-Oriented verification of programs is developed
Numerical Study of Ignition Transient in Solid Fuel Ramjets
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
Solid fuel ignition transient in dump combustor geometry is numerically studied. The objective of this work is to gain insight into the ignition of the fuel and its controlling parameters in back-step turbulent flow. The system of governing equations is solved with a finite volume approach using a structured grid in which the AUSM+ scheme is used to calculate the gas phase convective fluxes. The Spalart-Allmaras turbulence model is used in these simulations. First, the auto-ignition of solid fuel subject to an inlet oxidizer flow at elevated temperatures is considered and distinct intervals in ignition delay time are studied. We have demonstrated that for inlet oxidizer streams with high...
Investigation of EDC Turbulent Combustion Model for Flameless Combustion Regime in a Certain Combustion Chamber
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
Reducing carbon emissions emanated from combustion of fossil fuels is a challenging problem and consumes huge amount of money that is put into research every year. Nitrogen oxides are among the most important pollutants which have been at the center of attention of industries and international environment protection organizations, especially due to their increased production by commercial aircrafts at higher altitudes of the atmosphere. Flameless is a combustion regime that has been independently discovered by different research teams while working on reducing nitrogen oxides from burning fossil fuels in the early 1990s, and afterwards has been studied for its exclusive characteristics in...
Design and Analysis of Microwave Frequency-Reconfigurable Antennas Based on Handedness Preserving Metasurfaces
, M.Sc. Thesis Sharif University of Technology ; Memarian, Mohammad (Supervisor)
Abstract
In the last two decades, reconfigurable antennas have attracted significant research attention. Utilization of such antennas can lead to decrease in cost and power consumption in modern communication systems. The main focus of efforts is on frequency reconfigurability using different mechanisms while maintaining desirable antenna characteristics over the tuning range. In this thesis, our goal is to design, analyze and fabricate a reconfigurable antenna based on the concept of polarization standing wave (PSW) in the X band using only a simple physical tuning mechanism. Two anisotropic handedness preserving mirrors (AHPM) are placed at both ends of a cylindrical cavity resonator, thus...
Optimization of Leaching of Platinum Group Metals from Spent Car Catalytic Converters
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
The catalytic converter converts 95 to 99 percent of the vehicle exhaust gases into environmentally friendly gases, which are installed between the engine and the vehicle's exhaust cistern. The catalyst contained in the converters includes a ceramic structure commonly used as an alumina, coated with metal catalyst of expensive metals of the platinum group (platinum, palladium and rhodium). The purpose of this project is to optimize the recovery of platinum group metals from automotive catalytic converters by hydrometallurgy by hydrochloric acid and oxygenated water as an additive using Design Expert software. In this project, using the factorial design, the effect of parameters of...
An Experimental-Theoretical Study on Batch (Static) Sublimation and Derivation of a Correlation for its Heat Transfer Coefficient
, M.Sc. Thesis Sharif University of Technology ; Otukesh, Mohammad (Supervisor)
Abstract
The major features of batch sublimation were investigated in an experimental-theoretical study. An experimental setup with real-time displays, sublimated dry ice blocks of different sizes, with circular or rectangular geometries. When temperature of hotplate was changed from -30 to 200 oC, heat transfer coefficient “hsub” decreased from 126 to 70 W/m2K, while thermal flux increased, linearly. Weight and area of the block had a positive/negative effects on “hsub”, respectively. In theoretical part, at first, two “linear-gradient” and “cubic” models were developed by a combined mass-momentum-energy balance. The latter used Von Karman temperature profile, and in cases of circular and...
Fair and Efficient Cake Cutting
, M.Sc. Thesis Sharif University of Technology ; Ghodsi, Mohammad (Supervisor)
Abstract
Cake Cutting is an old problem that studies how to allocate a resource among a number of agents to achieve fairness or maximize the revenue by selling the chunks fairly. The primary assumption in the conventional methods of studying Cake Cutting was that the allocator knows everything about the agents and their valuation functions for the different cuts of the cake, which could be impossible in real life. Here we addressed a new setting for an online Cake Cutting problem with unconnected pieces and studied four different objectives upon the setting. There we studied fair and efficient Online Cake Cutting by means of linear fairness and envy freeness. We also added a payment rule to study the...