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soleimani--hosein
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Study of Effective Parameters on Helium Liquefaction Cycle using Exergy Analysis
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hosein (Supervisor)
Abstract
Liquefaction of gases is one of the applications of cryogenic science. Among the gases, Helium has the lowest boiling point, which at a pressure of 1atm is approximately 4.2K. Liquid helium can be used to cool superconductors in transportation equipment, military radars, and medical imaging equipment. For helium liquefaction, various cycles are used; these cycles have different parameters in their structure such as of input mass fraction to expanders, heat exchanger effectiveness, expander arrangement and ... which their analysis for improving the performance of the cycle is important. In this research, the aim is to study 2, 3 and 4 expander cycle with various parameters and structure. For...
Know-how-first anti-intellectualism: Williamson against Williamson
, Article Synthese ; Volume 200, Issue 4 , 2022 ; 00397857 (ISSN) ; Khalaj, M. A ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Inspired by Williamson’s knowledge-first epistemology, I propose a position on practical knowledge that can be called the ‘know-how-first view’; yet whereas Williamson is one of the pioneers of the new intellectualism about know-how, I employ the know-how-first view to argue against intellectualism and instead develop a know-how-first version of anti-intellectualism. Williamson argues that propositional knowledge is a sui generis unanalyzable mental state that comes first in the epistemic realm; in parallel, I propose that know-how is a sui generis unanalyzable power that comes first in the practical realm. To motivate this suggestion, I put forward two arguments: (1) drawing on...
An Investigation of a Fuzzy Transformation of Variables on the Robustness of Choice Models
, M.Sc. Thesis Sharif University of Technology ; Pourzahedi, Hosein (Supervisor)
Abstract
Estimation of demand, for example, for transportation is an important issue for the planning and programming of various systems. Thus, enhancing the predictability power of such models is of high value. Demand stems from choices of individuals, and choice is subject to uncertainty and fuzziness. Uncertainty comes from many factors including incomplete information of decision-maker, and fuzziness comes from many other factors including personal perception regarding the value of the variables affecting choice. This study tries to introduce a new approach in building choice models, in which variables are transformed into another variable by the help of a global wisdom. This wisdom shows the...
Study of the Interaction of Non-level Crossing Tunnels, Case Study of Crossing of Tunnels of Line 1 and Line 7 of Tehran Metro
, M.Sc. Thesis Sharif University of Technology ; Sadaghiani, Mohammad Hosein (Supervisor)
Abstract
As the crowded cities require public transportation and because of lack of space on the ground, Subway and boring underground tunnels encountered. In this thesis the interaction of boring the line 7 of Tehran metro with the existing station of line 1 of Tehran metro (Molavi station) is studied. By changing the soil specification, The surface settlement is significant so the soil specification is one of the important parameters of the interaction. For comparinf the effect of these parameters, the soil settlement and bending moments is investigated in different parts of station while the lower tunnel is passing beneath it. The 3D Abaqus software is used for modeling this interaction. In...
Text to Phoneme Transcription Capable to Detect Ezafe and Homographs for Persian Speech Synthesis
, M.Sc. Thesis Sharif University of Technology ; Sameti, Hosein (Supervisor)
Abstract
In Persian language, there are some special uncertainties and complexities regarding the extraction of phonemes due to its flexible structure. In this work, we try to solve two problems caused by this issue, homographs disambiguation and Ezafe recognition in Persian text to speech systems.
In this work, two methods are presented for solving the two problems. The first one is a pattern recognition method based on Aho-Corasick algorithm that has the best performance according to the execution time. The second method is a hidden Markov model tagger based on Viterbi algorithm that uses bigram and trigram statistics. These methods are run on 10 million word corpus and the results are compared...
In this work, two methods are presented for solving the two problems. The first one is a pattern recognition method based on Aho-Corasick algorithm that has the best performance according to the execution time. The second method is a hidden Markov model tagger based on Viterbi algorithm that uses bigram and trigram statistics. These methods are run on 10 million word corpus and the results are compared...
Predictive and Nonlinear Control of Aircraft in Presence of Microburst Wind Shear
, M.Sc. Thesis Sharif University of Technology ; Pourtakdoust, Hosein (Supervisor)
Abstract
Airplanes usually experience minor position change and height loss during cruise flight, but under normal circumstances the aircraft total energy is adequately acceptable to maintain the trajectory and the desired performance without severe oscillations. On the other hand, if the airplane encounters a wind-shear or microburst during take-off or landing phases, it would be a dangerous situation, as the aircraft kinetic and potential energy levels are not as high.
In this research, a model predictive controller is designed and investigated to allow a transport category aircraft to either escape or penetrate the microburst. In this regard, initially a DMC controller is designed for 6-DoF...
In this research, a model predictive controller is designed and investigated to allow a transport category aircraft to either escape or penetrate the microburst. In this regard, initially a DMC controller is designed for 6-DoF...
Study of Loading Orientation Effect on Shear Strength of Rock Mass Discontinuities with Infilling Based on Laboratory Methods
, M.Sc. Thesis Sharif University of Technology ; Sadaghiani, Mohammad Hosein (Supervisor)
Abstract
Recently, Needs for construction of rock structures and underground ones such as tunnels, dam foundations, power plants and caverns built to keep oil, gas and nuclear waste has increased dramatically. In order to design, construct and excavate these underground structures safely and economically, full understanding of rock mass properties, suitable tools and practical techniques of drilling are necessary. Because of existing this discontinuities, including joints and layered rock masses and their effects on mechanical behavior of rock mass, it is necessary for the geomechanical profile, shear strength and failure mechanism of rock mass to be accurately indentified. Shear strength criterions...
Verifying the Empirical Validity of the Trilemma using U.S. Monetary Shocks
, M.Sc. Thesis Sharif University of Technology ; Barakchian, Mahdi (Supervisor) ; Joshaghani, Hosein (Co-Supervisor)
Abstract
According to the impossible trinity, countries can only enjoy from two of the following choices simultaneously: fixed exchange rate, free capital flow and independent monetary policy. A part of the economics literature has tried to verify the theory empirically. Some of the researches like Klein and Shambugh(2015) has concluded that the trilemma is valid on the occasion of transferring the effect of base countries interest rate changes to other countries. On the other side, a few papers like Ray(2013) has shown that an independent monetary policy can just be obtained by a closed capital flow and a float exchange rate system can not necessarily give central banks the autonomy of monetary...
Design and Implementation a Controller for a XY Nano-Positioning System using Piezo Stack with Strain Gauge Fitted
, M.Sc. Thesis Sharif University of Technology ; Nejat, Hosein (Supervisor) ; Salarieh, Hassan (Supervisor)
Abstract
Nanopositioning is the technology to control position of the objects with precision of the scale of nanometers. Nowdays, This technology emerged as one of the components of research and production in the micro and nanometer dimensions, helping researches and producers to carry out many state of the art projects. A nanopositioning device, consists of a support to path guidance, an actuator to apply force and motion, a driving circuit for communication with the actuator, a sensor for measuring displacement, a circuit for reading sensor’s data, a controlling algorithm to reach the desired precision, a controlling hardware to enforce controlling logic, a power supply and a graphical user...
Throughput analysis of a cognitive multi-hop IEEE 802.11-based WLAN overlaid on a cellular network
, Article 2011 International Conference on Software, Telecommunications and Computer Networks, SoftCOM 2011, 15 September 2011 through 17 September 2011, Split, Hvar, Dubrovnik ; 2011 , Pages 307-311 ; 9789532900262 (ISBN) ; Ashtiani, F ; Sharif University of Technology
2011
Abstract
In this paper, we focus on a cognitive network scenario, comprised of a multi-hop IEEE 802.11-based WLAN overlaid on a cellular network. In this scenario, the wireless nodes in a WLAN, i.e., cognitive nodes, use the downlink frequency channels of the cellular network opportunistically, such that at each packet transmission all idle channels have been exploited. In order to evaluate the capability of the considered cognitive network scenario, we propose an open queueing network model such that different packet transmission phases are mapped onto different queueing nodes. We also map different types of collisions, i.e., collision on control signals as well as collision on data transmission due...
Synergistic strengthening by severe plastic deformation and post-heat treatment of a low-carbon steel
, Article Steel Research International ; Volume 89, Issue 6 , 2018 ; 16113683 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Wiley-VCH Verlag
2018
Abstract
Low-carbon steel sheets are severely plastic deformed to strains of up to ≈3.48 and subsequently heat treated by conventional annealing followed by water-quenching. Four temperatures are chosen for the annealing below and over the Ac1 and Ac3 transformation lines. The effects of post-deformation heat treatment are investigated by evaluating the microstructure and mechanical properties, including strength, ductility, work hardening capability, and hardness. A maximum increase of 86% in the strength is obtained through intercritical annealing and quenching of the samples subjected to strain of 1.16. It is interesting that both the elongation and ultimate tensile strength values are higher...
Multi-agent programming to enhance resiliency of earthquake-prone old metropolitan areas by transit-oriented development under public-private partnership
, Article European Journal of Transport and Infrastructure Research ; Volume 21, Issue 1 , 2021 , Pages 19-52 ; 15677141 (ISSN) ; Poorzahedy, H ; Sharif University of Technology
TU Delft
2021
Abstract
Deteriorated urban areas in large cities have poor living standards, are inaccessible and small-sized, and have unstable building structures. Earthquake hazards may turn such situations into human disasters. In most cases, neither the governments nor the owners of these properties have enough budgets for renovating them. The purpose of this paper is to take advantage of Transit Oriented Development concepts to simultaneously solve two major urban area problems: (a) renovation of deteriorated urban areas and prevention of urban sprawl, and (b) design of transit network and promotion of transit-oriented development to reduce traffic congestion, pollution, and other unwanted outcomes of the...
Application of survival model to reveal influential objective and subjective variables to educate old metropolitan area residents in trading lands for housings: case of Tehran
, Article Journal of Housing and the Built Environment ; 2022 ; 15664910 (ISSN) ; Poorzahedy, H ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Deteriorated land-uses constitute vast portions of the metropolitan areas, being small lots of land, hardly accessible, structurally unstable, and extremely vulnerable to moderate earthquakes. We present the results of a stated preference survey done to support the viability of administering a novel tri-lateral Public–Private Partnership of Build-Operate-Transfer type proposal of Government (G)-Residents (R)-Private Sector Investors (P). In this proposal, the (low income) R in a zone trade their lands for an equivalent value of safe housing built by P next to a newly constructed Bus Rapid Transit line built by G in the same zone, thus a Transit-Oriented Development. P, in return, receives...
Throughput Analysis of a Cognitive Multi-hop Wireless Network Overlaid on a Cellular Network
, M.Sc. Thesis Sharif University of Technology ; Ashtiani, Farid (Supervisor)
Abstract
In this thesis, we evaluate the maximum stable throughput of a cognitive multi-hop IEEE 802.11-based WLAN overlaid on a cellular network. In the considered scenario, the secondary users operate in the downlink or uplink frequency band of primary network and transmit their data in free primary channels using OFDM technique. The activity of primary nodes is modeled independently by ON-OFF alternating states. To model the scenario, each secondary user is modeled with an open queueing network. The queueing network can model the transmission of data as well as the effect of primary users. By writing the traffic equations of the queueing network and applying the stability conditions, we are able...
Analysis of the Effect of Frame Aggregation in IEEE 802.11 Standard
, M.Sc. Thesis Sharif University of Technology ; Ashtiyani, Farid (Supervisor)
Abstract
In this thesis the effect of frame aggregation mechanism in maximizing throughput in Wireless Local Area Networks (WLANs) have been investigated. Frame aggregation has become a part of the IEEE 802.11 standard as the amendment IEEE 802.11n. First, we have a quick review on access control layer in IEEE 802.11 standard then illustrate the necessity of frame aggregation. Afterwards, we propose an analytical model for the analysis of an IEEE 802.11n network comprised of an Access Point (AP) and several conventional nodes, all in the coverage area of each other. This analytical model focuses on downlink throughput; therefore only AP uses frame aggregation and the other nodes use basic IEEE 802.11...
Deep Learning For Recommender Systems
, M.Sc. Thesis Sharif University of Technology ; Soleimani, Mahdieh (Supervisor)
Abstract
Collaborative fltering (CF) is one of the best and widely employed approaches in Recommender systems (RS). This approach tries to fnd some latent features for users and items so it would predict user rates with these features. Early CF methods used matrix factorization to learn users and items latent features. But these methods face cold start as well as sparsity problem. Recent years methods employ side information along with rating matrix to learn users and items latent features. On the other hand, deep learning models show great potential for learning effective representations especially when auxiliary information is sparse. Due to this feature of deep learning, we use deep learning to...
Development of Cascade Fuzzy Filters in Integrated INS-DVL-GPS Navigation
, M.Sc. Thesis Sharif University of Technology ; Salarieh, Hassan (Supervisor)
Abstract
Navigation is the science of determining the velocity and attitude of a moving object in every given moment. There have been many methods for navigation. Nowadays with the advancement of technology, advanced navigation systems have been developed. Although each of these navigation systems have their pros and cons, in order to improve the overall performance of the system and to solve their problems, these systems are integrated.The goal of this project is to present an integrated cascade method to decrease error and also decrease dependence on GPS. In this project, INS, DVL & GPS are integrated with the cascade method.To achieve this, INS-GPS and INS-DVL integration are first performed. The...
A Mathematical Model for Pricing and Container Repositioning in a Competitive Transportation Network
, M.Sc. Thesis Sharif University of Technology ; Najafi, Mehdi (Supervisor)
Abstract
The transportation is one of the important components in the economies of different countries. In the maritime transportation network, the demand is usually not balanced in different routes, and this imbalance results to accumulation of containers in a node. In order to sustain the problem, firms have to reposition empty equipment from a surplus location to a shortage location, which causes the problem of “Empty Repositioning Problem”. In this study, pricing strategies in one transportation market with two locations are considered; while there is ERP problem in issue. The problem is solved by Bertrand game method. The research is divided into two parts of the monopoly network and the duopoly...
Microstructure Modification and Electrical Conductivity Development in PA6/PS Blend using PANI Coated CNT
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor)
Abstract
In this research, a nanocomposite blend of polyamide 6/polystyrene containing polyaniline-coated carbon nanotubes was fabricated via melt blending method, aiming to achieve electrical conductivity in the range of static dissipation. The effect of weight percentage of nanofillers and surface modification of carbon nanotubes with polyaniline on the electrical properties and microstructure of the nanocomposite was investigated. To promote compatibility between the immiscible polyamide 6 and polystyrene polymers, PS-g-MA compatibilizer was utilized, and its effect on the morphology of the nanocomposite blend was examined. Additionally, the influence of weight percentage of nanofillers and the...
Assessment of Vulnerability and Resilience to Land Degradation
, M.Sc. Thesis Sharif University of Technology ; Moghim, Sanaz (Supervisor)
Abstract
In recent decades, especially with the increase of greenhouse gases and global warming, land degradation has become one of the important global environmental issues. Land degradation has significant impacts on soil performance, vegetation cover, crops, and even the dispersion of dust particles. Land degradation is a complex phenomenon that is affected by multiple factors. Thus, it is necessary to identify these factors and then assess the degree of vulnerability and resilience to it globally. Proper indicators can clarify the integration and effective linkage between related parameters. This study aims to develop a Land Degradation Vulnerability Index (LDVI) using parameters such as...