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mohammadian-roshan--yaser
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Fuzzy Fractional Order PID Design
, M.Sc. Thesis Sharif University of Technology ; Sadati, Naser (Supervisor)
Abstract
In this thesis a novel Fuzzy Fractional Order Controller (FFOPID) is presented. This controller is designed by the means of the combination of a fuzzy system and a fractional order PID. Fractional controllers, especially fractional PIDs, shows their performance in control systems after the advent of fractional calculus. Fractional PID has better flexibility according to the classic PID. As the real control systems are nonlinear actually, so solving the control problem needs a nonlinear controller. Therefore, a fuzzy system is used in this thesis, in order to adapt the controller parameters with different operating points of the system. Fuzzy system design needs the optimal values for...
Risk Action Plans’ Cost Optimization by Considering Risks’ Interdependency
, M.Sc. Thesis Sharif University of Technology ; Shadrokh, Shahram (Supervisor)
Abstract
Risk management, one of the knowledge areas in project management, plays a key role in the success of projects in today’s unstable situation. The massive cost reduction achieved by risk management can manifest its importance even more in huge construction projects in gas and oil industry such as developments of power plants and petrochemical complexes. In this research, the effect of considering the correlation between risks and consequently the effect of risk action plans on other risks in their execution cost reductions has been demonstrated. A questionnaire has been designed, many experts have been interviewed, and using statistical methods, the risks’ interdependencies have been...
RANS simulations of the stepped duct effect on the performance of ducted wind turbine
, Article Journal of Wind Engineering and Industrial Aerodynamics ; Volume 145 , October , 2015 , Pages 270-279 ; 01676105 (ISSN) ; Alimirzazadeh, S ; Rad, M ; Sharif University of Technology
Elsevier
2015
Abstract
With the rise in oil price and population growth, renewable energies are assumed to be the main source of energies for the next generation. Wind as a natural, eco-friendly and renewable source of energy has been at the center of concentration for decades. Recently there has been some ideas regarding the self-regulating urban wind turbines. Researchers have shown that a proper enclosure increases the wind velocity and therefore more torques can be exerted on the rotors, therefore more power can be generated. These enclosures are light and cheap, therefore they are applicable and effective. In the present study, an enclosure was modified to increase the exerted torque with implementing a step...
Recognition and the Nature of Self-consciousness in Fichte and Hegel
, M.Sc. Thesis Sharif University of Technology ; Abazari, Arash (Supervisor)
Abstract
For both Fichte and Hegel, self-consciousness is an intersubjective concept; that is, for them, self-consciousness is necessarily constituted between, at least, two subjects. In Foundations of Natural Right, Fichte introduces summons and recognition as necessary conditions of self-consciousness, without which, i.e. an other who is calling upon the subject, the subject cannot be conscious at all. Hegel, in Phenomenology of Spirit, also says self-consciousness is desire which is satisfied only in another (self-) consciousness. Based on these ideas, I try to show that self-consciousness can be defined as having the both in view; the self (I) and the other (not-I), at the same time. In this...
Design, Manufacture and Flight Dynamics Analysis of A Handlaunched Solar UAV
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
Hand-launched UAVs are type of unmanned aerial vehicles that due to transportability and geometric specification, are operationally valuable and worthy. reconnaissance & surveillance (aerial mapping, aerial filming, inspection, border protection); health care (blood transport, body organ transport, medicine delivery); agriculture (farm monitoring, fertilization, cloud seeding); payload delivery (envelopes posting); network covering (internet supply, telecommunication relay); crisis management (remote area medical) are some of typical applications and missions of this type of aircrafts. These UAVs have almost low altitude short endurance (below 5000 ft. and less than 2 hrs.). To extend their...
Performance Improvement of Maximum Power Point Tracker in Grid-Connected Photovoltaic Systems
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
Increase in growing concerns over environmental pollution and depletion of fossil fuel resources motivate the need for cleaner energy technologies and stimulate research in facilitating renewable energy systems. In recent years, photovoltaic systems have attracted great attention since they remove the need for energy storage systems and intermediate processess for energy conversion. However, high capital cost, low efficiency and low energy density per area of these systems, as compared with other technologies hinder its industrial use. To surmount these bottlenecks and improve technical performance of PV systems, it is crucial to optimize configuration of convertor connection and to improve...
Compressive Behavior of Confined Concrete Column with FRP Layers
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In recent years, the use of fiber reinforced polymer (FRP) jackets, as an external lateral confinement has found considerable attention in retrofitting and strengthening existing reinforced concrete (RC) columns in earthquake prone areas. The FRP composites have numerous advantages such as ease in application, high strength and stiffness-weight ratio, no corrosion and negligible changes in the member dimension. Most of previous studies have concentrated on evaluation of the effect of confinement with spiral bars or FRP composites, separately. However, in practice both types of confinements exist in strengthening RC columns.
This paper presents the results of a computational modeling to...
This paper presents the results of a computational modeling to...
An Approach to Improve the Security of Big Data
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasool (Supervisor)
Abstract
Different data sources are creating a huge amount of data at increasing speeds that require real-time processing. Such data is called “Big data stream". Although, mining and analysis this type of data is so useful for companies, but it also may cause many privacy breaches. The principle issues for big data stream’ anonymization are real time processing and information loss. There are some works that are proposed for data streams, but they have some drawbacks such as inefficient anonymization of big data stream and also not consider time expiration of tuples that lead to increase the information loss and cost of the data publishing. In this thesis, in order to speed up the ability of big data...
Hybrid Approach based on QFD for Improving the Selection of Product Suppliers
, M.Sc. Thesis Sharif University of Technology ; Mostafavi, Mostafa (Supervisor)
Abstract
Multi-Criteria Decision-Making models have been considered by many researchers in recent years. In this study, considering the transition matrix, the probability of changing in the priories of the customers in the framework of a hybrid QFD-ANP has been proposed. The developed methodology is implemented to solve the supplier selection problem, one of the most important problems in the supply chain management, in a dairy manufacturer in Iran. The company is one of the most prominent companies that has a big segment of the dairy market. The results show the efficiency of the proposed methodology for multi-criteria decision-making problems.• Chapter 1) General research reasons for the purpose...
Iran’s oil development scenarios by 2025 [electronic resource]
, Article Energy Policy ; Volume 56, May 2013, Pages 612-622 ; Sharif University of TechnologyUnsteady RANS simulation of a surface piercing propeller in oblique flow
, Article Applied Ocean Research ; Volume 56 , 2016 , Pages 79-91 ; 01411187 (ISSN) ; Zabihzade Roshan, S ; Seif, M. S ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Conventional propellers might undergo severe cavitation at high speeds and this phenomenon not only affects the efficiency of the propeller, but also may result in serious damages in propulsion system. Due to their special geometries, surface piercing propellers (SPPs) overcome this problem and achieve high efficiencies in high speeds. Therefore, SPPs are one of the popular propulsors for high-speed crafts. The present research is aimed to pursue SPP's performance in the off-design conditions. URANS method was used to study the performance of the 841-SPP (case with some available experimental results; Olofsson, 1996) in several immersion ratios (= 33%, 50%, 75% and 100%) and maneuvering...
Discovering and Improving the Processes of an Iranian Psychiatric Hospital Using Process Mining
, M.Sc. Thesis Sharif University of Technology ; Hassan Nayebi, Erfan (Supervisor)
Abstract
Providing quality hospital services depends on the efficient and correct implementation of processes. Therapeutic care processes are a set of activities that are carried out with the aim of diagnosing, treating and preventing any disease in order to improve and promote the patient's health. The purpose of this study is to use process mining techniques to discover and improve healthcare processes. The case study of this research is a psychiatric hospital in Shiraz. The approach implemented in this research consists of three main stages including data pre-processing, model discovery phase, and analysis phase. Three algorithms including Heuristic Miner, Inductive Miner, and ILP Miner were used...
Modelling the Physics of Collective Decision Making and Commuication by Signal Exchange
, Ph.D. Dissertation Sharif University of Technology ; Rouhani, Shahin (Supervisor) ; Roudi, Yaser (Co-Supervisor)
Abstract
In many biological populations, information about environmental conditions is acquired collectively, through information sharing among individuals, by exchanging signals. In order to achieve a better understanding of such systems, using methods borrowed from statistical physics, we introduce two mathematical models. First, a collective decision making model, for a community of individuals residing on a communication network, who live in an uncertain environment, in which individuals try to collectively find the environmental state. In the second model, a collective movement model, we consider a population of collectively moving individuals, in which individuals try to collectively find and...
Imaging Method To Detect Low Probability of Intercept Radars
, Ph.D. Dissertation Sharif University of Technology ; Nayebi, Mohammad Mahdi (Supervisor) ; Norouzi, Yaser (Co-Advisor)
Abstract
In this thesis, a new passive method suitable for Geolocating LPI radars is introduced. The method uses two Electronic Support (ES) receivers placed on a fast moving platform (e.g., an airplane or a satellite). The proposed method has a high processing gain, which makes it highly suitable for very weak LPI signals. The processing gain of the method was analytically derived and illustrated with simulation to determine if the proposed method can detect LPI radars in much lower SNRs compared to regular time-frequency LPI detection methods. Also, the resolution of the proposed method in both range and cross-range direction in radar location finding was analyzed. Furthurmore, the effect of the...
Crystallization of hydroxyapatite during hydrothermal treatment on amorphous calcium phosphate layer coated by PEO technique
, Article Ceramics International ; Volume 39, Issue 2 , 2013 , Pages 1793-1798 ; 02728842 (ISSN) ; Arbabi, A ; Mehdinezhad Roshan, A ; Sharif University of Technology
2013
Abstract
Surface modification of titanium implants is recently considered by several researchers. In this study, PEO was performed over commercially Ti-6Al-4V alloy pellets in an aqueous electrolyte containing calcium acetate (C.A.) and calcium glycerphosphate (Ca-GP) with a Ca/P molar ratio of 6.8, and applying current density of 0.212 A/cm2, frequency of 100 Hz and duty ratio of 60% for 4 min. In the next step, hydrothermal treatments were carried out for various durations and at different temperatures inside an autoclave chamber containing a NaOH solution with pH of 11.5. XRD and SEM results confirmed formation of needle-shaped HAp after all hydrothermal conditions. Maximum intensity of HAp peaks...
A behavioral analysis of freight mode choice decisions
, Article Transportation Planning and Technology ; Volume 34, Issue 8 , 2011 , Pages 857-869 ; 03081060 (ISSN) ; Kawamura, K ; Mohammadian, A ; Sharif University of Technology
2011
Abstract
This paper develops a behavioral analysis of freight mode choice decisions that could provide a basis for an acceptable analytical tool for policy assessment. The paper specifically examines the way that truck and rail compete for commodity movement in the US. Two binary mode choice models are introduced in which some shipment-specific variables (e.g. distance, weight and value) and mode-specific variables (e.g. haul time and cost) are found to be determinants. The specifications of the non-selected choice are imputed in a machine learning module. Shipping cost is found to be a central factor for rail shipments, while road shipments are found to be more sensitive to haul time. Sensitivity of...
Commutativity of the adjacency matrices of graphs
, Article Discrete Mathematics ; Volume 309, Issue 3 , 2009 , Pages 595-600 ; 0012365X (ISSN) ; Moazami, F ; Mohammadian, A ; Sharif University of Technology
2009
Abstract
We say that two graphs G1 and G2 with the same vertex set commute if their adjacency matrices commute. In this paper, we find all integers n such that the complete bipartite graph Kn, n is decomposable into commuting perfect matchings or commuting Hamilton cycles. We show that there are at most n - 1 linearly independent commuting adjacency matrices of size n; and if this bound occurs, then there exists a Hadamard matrix of order n. Finally, we determine the centralizers of some families of graphs. © 2008 Elsevier B.V. All rights reserved
Simulation of startup operation of an industrial twin-shaft gas turbine based on geometry and control logic
, Article Energy ; Volume 183 , 2019 , Pages 1295-1313 ; 03605442 (ISSN) ; Saidi, M. H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this paper, a transient model is developed to simulate the start-up operation of an industrial twin-shaft gas turbine based on real geometry and control logic. The components’ characteristic curves of the studied gas turbine were generated with the aid of CFD simulation tools and according to the real geometry of each component. The control logic of the studied gas turbine was simplified and coupled with the developed engine performance model. Also, the gas turbine actuators including variable inlet guide vanes, compressor bleed valves, and fuel valves were simulated so that their concurrent effects on the gas turbine transient behavior can be captured precisely. Moreover, the air-cooled...
Commuting graphs of matrix algebras
, Article Communications in Algebra ; Volume 36, Issue 11 , 2008 , Pages 4020-4031 ; 00927872 (ISSN) ; Bidkhori, H ; Mohammadian, A ; Sharif University of Technology
2008
Abstract
The commuting graph of a ring R, denoted by Γ(R), is a graph whose vertices are all noncentral elements of R, and two distinct vertices x and y are adjacent if and only if xy = yx. The commuting graph of a group G, denoted by Γ(G), is similarly defined. In this article we investigate some graph-theoretic properties of Γ(Mn(F)), where F is a field and n ≥ 2. Also we study the commuting graphs of some classical groups such as GLn(F) and SLn(F). We show that Γ(Mn(F)) is a connected graph if and only if every field extension of F of degree n contains a proper intermediate field. We prove that apart from finitely many fields, a similar result is true for Γ(GLn(F)) and Γ(SL n(F)). Also we show...
Studying and Modeling Climatic and Terrestrial Factors Effect the Occurrence of Dust Phenomena, and Determining the Origin of Dust Storms in IRAN
,
M.Sc. Thesis
Sharif University of Technology
;
Farhanieh, Bijan
(Supervisor)
Abstract
Particulate matter is an important source of air pollution. Particulate matters have an Undesirable effect on the environment, economic, and the health of Tehran Citizens. Annually, more than 8 thousands of tons of mineral dust from Internal and external resources deposit in Tehran city. In this project, the increase in the level of PM10 concentration during June, 12th to 14th, 2015 have been considered. The intrusion and dispersion of mineral dust during June, 11th to 15h, 2015 have been simulated with the HYSPLIT Model. Also, the Trajectory of particle end in Tehran during the mentioned days simulated and plotted with the HYSPLIT. The results show that more than 85% of PM10 reported by Air...