Maneuvering & Dynamic Stability Study of Planing Hulls

, Ph.D. Dissertation Sharif University of Technology Fathi Kazerooni, Mohammad Reza (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

Planing hulls have been under rapid development during recent years and their maximum speed has increased significantly thanks to advancements in high power engines and light weight hull construction methods. In the past two decades, the main concern have been hydrodynamic characteristics and stability of the planing hulls in straight-line motion in calm and rough water, and no applied mathematical model is proposed for their dynamic motions in different maneuvers in contrast to displacement hulls. Moreover, control loss at high speeds is very prevalent and in most cases this leads to economy and human losses. The main target of this thesis is to develop and validate a mathematical model to...

On the scale effects of resistance model tests of high-speed monohulls

, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 41, Issue 4 , 2019 ; 16785878 (ISSN) Fathi Kazerooni, M ; Seif, M. S ; Sharif University of Technology

Springer Verlag 2019

Abstract

Scaled model test in towing tank is a common method to predict the ship resistance in calm water. The scale effects are dominant in these tests because the Reynolds and Froude numbers of the model and full-scale ship cannot be equal. There is a sufficient amount of knowledge about the displacement hulls which have limited speed ranges in most cases. However, scarcity of published data on high-speed crafts is noticed. The influence of the model length on ship resistance varies in different speeds, so it should be studied in more detail. The extrapolation method of model ship resistance to full scale is studied in this paper for high-speed monohulls. Resistance model tests of semi-displacement...

Numerical Simulation of Displacement of the Fluid Phases in Porous Media

, M.Sc. Thesis Sharif University of Technology Fathi Kazerooni, Hamed Reza (Author) ; Moosavi, Ali (Supervisor)

Abstract

Nowadays, oil has an important role in our life and most of its role can be seen on the transportation. Discovering and extraction of oil are very important to produce oil and receive it to costumer. When oil is discovered, the oil companies used to drill the ground to extract the oil but they can’t extract all of oil from its reservoir. So, researchers proposed to inject another fluid like water to the oil reservoir to extract oil. Oil is trapped in the porous media which has a lot of pores and some of them have a micro scale size and they contain oil. When water is injected to the reservoir it flows in this pore and interfaces with oil and they create a multiphase flow. The governing...

Post Fault Vector Control of CHB Driven Induction Motor

, M.Sc. Thesis Sharif University of Technology Fathi, Manochehr (Author) ; Zolghadri, Mohammad Reza (Supervisor)

Abstract

Multilevel converters are considered recently as one of the industrial solutions for high-power and power quality demanding applications. Casacade H-Bridge (CHB) converter is one of the well known topologies among multilevel converters. CHB converter is characterized by its high modularity allowing its power to be easily increased. Modularity also allows any faulty cell to be isolated, so the load can be fed by the remaining operative cells, which leads to an unbalanced output voltage of the CHB converter. To avoid the unbalanced operation, recently a solution based on modifying the phase and the magnitude of the voltage refereces has been proposed. This thesis presents a method to control...

Chitosan/Gelatin/Mg Substituted Hydroxyapatite Nano Composite Scaffold for Bone Tissue Engineering

, M.Sc. Thesis Sharif University of Technology Azamian, Fariba (Author) ; Mohammadi, Mohammad Reza (Supervisor) ; Fathi, Mohammad Hossein (Co-Advisor)

Abstract

The present study is work on fabrication and characterization of a chitosan/ gelatin/ Mg substituted hydroxyapatite nano composite scaffold for bone tissue engineering. At the first step pure and Mg-substituted hydroxyapatite (HA) (Ca10-xMgx(PO4) 6OH2) nano-hexagonal rods with 14–45 nmdiameter.for this, calcium nitrate, magnesium phosphate hydrate and potassium dihydrogenphosphate were used as precursors for Ca, Mg, and P, respectively. Calculated amounts of magnesium ions (Mg+2) especially from 0 to 8% (molar ratio) were incorporated as substituted into the calcium sol solution. Deionized water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH= 9....

Simulation of 2D and Two-Phase Flows in Porous Media Using MLPG Method

, M.Sc. Thesis Sharif University of Technology Fathi, Abdolhamid (Author) ; Pishvaie, Mahmoud Reza (Supervisor) ; Bazargan, Mohammad (Supervisor)

Abstract

Conventional methods of solving partial differential equations such as finite difference method, finite volume method, and finite element method require mesh generation in the problem domain. When these methods are applied to solve problems involving shock propagation, crack propagation or deformable domain, or in the case of mesh refinement, multiple mesh regenerations are needed which is laborious and time consuming. In recent years, meshless methods have been developed to avoid difficulties of mesh-based methods. Meshless Local Petrov-Galerkin (MLPG) method is a truly meshless method that does not rely on mesh neither in function approximation nor in the integration of the weak form. In...

Modeling the Nonlinear Behavior of Nano-Materials Via Hierarchical RVE-based Multi-Scale Method

, M.Sc. Thesis Sharif University of Technology Nikravesh Kazerooni, Yousef (Author) ; Khoei, Amir Reza (Supervisor)

Abstract

In this paper, a hierarchical RVE-based continuum-atomistic multiscale framework is established on the basis of the nonlinear finite element method and molecular dynamics simulation in order to model the geometric and material nonlinearities of deformable solids. In this framework, the coarse scale material properties required for nonlinear finite element method are directly exploited via fine scale atomistic simulation of atomic RVEs designated for each coarse scale integration point and required boundary conditions for atomic RVE simulation are achieved from the coarse scale kinematical response. In order to ensure the kinematical and energetic consistency between the two scales, the...

Experimental Study of Common Refrigerants Replacement with Hydrocarbon Mixture in Automotive Air Conditioning System

, M.Sc. Thesis Sharif University of Technology Fathi, Davood (Author) ; Soltanieh, Mohammad (Supervisor)

Abstract

Due to the environmental concern for the harmful effect of the release of HFCs on global warming there has been more interest for the use of hydrocarbons as refrigerants in recent years. In this project the performance of these refrigerants have been studied and compared with common refrigerants from the quantitative and qualitative point of view using a real-scale model of Peugeot-405 air conditioning system. Charging amount, inside temperature, cooling load, energy consumption of cycle, coefficient of performance and required time to steady state condition are the important comparative criteria for such a study. After carrying out a series of tests it has been considered that charge...

Perusing Metal Perusing Metal Insulator Transistors with in the Dynamical Field Approximation at Finite Temperature

, Ph.D. Dissertation Sharif University of Technology Fathi, Mohammad Bagher (Author) ; Vesaghi, Mohammad ALi (Supervisor)

Abstract

The aim of this work is to investigate some theoretical models developed in recent years for describing electronic correlation and apply them to some special problems and metallicity and insulating behavior of one type of paramagnetic systems. One of the vast‐applied and effective routines for investigating the strongly correlated electron systems is Dynamical Mean Field Theory (DMFT). In the first part, the equations of DMFT are solved on nearly real frequency axis with a effective and more reliable solver a little parameter γ above the real axis. This approach appears fine structures that can’t be captured with the ...

A Dynamic Slack Management Technique for Low Energy Consumption in Real-time Multi-core Embedded Systems

, M.Sc. Thesis Sharif University of Technology Fathi, Mohammad Hossein (Author) ; Ejlali, Alireza (Supervisor)

Abstract

Due to the increasing development of digital systems based on limited energy sources (i.e. battery), energy efficiency has become one of the most important concerns in the design of these systems. The use of multi-core architecture is an effective solution for the problem of reducing energy consumption. Hence using it in digital systems has become more common. In addition, enabling methods for reducing energy consumption on processor, helps in making energy more efficient. DVFS and DPM are the two major methods used for reducing dynamic and static energy consumption of processors. The using of multi-core architecture due to the higher chip density, results the static and dynamic energy...

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...

Scheduling and Allocation of Pandemic Vaccine Distribution Among Healthcare Centers and High-risk Groups

, M.Sc. Thesis Sharif University of Technology Fathi, Mohammad Reza (Author) ; Eshghi, Kourosh (Supervisor)

Abstract

This study offers a framework to manage mass vaccination programs in response to an outbreak in a city. Compared to previous studies, we consider more operational challenges in the vaccination process; for example, transshipment between vaccinations units and availability of second doses. Our objective function is based on the risk of unvaccinated individuals. Therefore, the model aims at favoring those places in the city where the risk of unvaccinated people is high. Using different kinds of vaccines is another factor that our mathematical model includes. Vaccines are categorized into single-dose and double-dose classes. In this regard, the balanced access to different vaccine types is of...

Plasmonic fractals: Ultrabroadband light trapping in thin film solar cells by a Sierpinski nanocarpet

, Article Optical and Quantum Electronics ; Vol. 46, issue. 6 , 2014 , pp. 751-757 ; ISSN: 03068919 Kazerooni, H ; Khavasi, A ; Sharif University of Technology

2014

Abstract

Plasmonic Sierpinski nanocarpet as back structure for a thin film Si solar cell is investigated. We demonstrate that ultra-broadband light trapping can be obtained by placing square metallic nanoridges with Sierpinski pattern on the back contact of the thin film solar cell. The multiple-scale plasmonic fractal structure allows excitation of localized surface plasmons and surface plasmon polaritons in multiple wavelengths leading to obvious absorption enhancements in a wide frequency range. Full wave simulations show that 109 % increase of the short-circuit current density for a 200 nm thick solar cell, is achievable by the proposed fractal back structure. The amount of light absorbed in the...

Effect of traffic-load dependent vehicle routing algorithm on the connectivity in VANETs

, Article IEEE Vehicular Technology Conference, 15 May 2011 through 18 May 2011 ; May , 2011 , Page(s): 1 - 5 ; 15502252 (ISSN) ; 9781424483310 (ISBN) Kazerooni, A ; Ashtiani, F ; Sharif University of Technology

2011

Abstract

In this paper, we evaluate how traffic-load dependent vehicle routing at intersections is able to improve the connectivity status of all streets. To this end, we consider a VANET scenario, comprised of several streets and intersections. Then, we focus on two vehicle routing algorithms, one based on the distance to destination, i.e., traffic-load independent (TLI) algorithm, and another one based on both distance to destination and traffic load status of the local streets, i.e., traffic-load dependent (TLD) algorithm. By employing a simple mobility model based on an open BCMP queueing network, we derive the spatial traffic distribution at two cases. Afterwards, we propose a simple algorithm...

Electrodeposition of the Ni-P by Pulse Plating

, M.Sc. Thesis Sharif University of Technology Kazerooni, Amir (Author) ; Dolati, Abolghasem (Supervisor)

Abstract

Ni-P alloy coatings were electrodeposited using pulse current in a watt type bath in various conditions. The influences of different parameters were investigated and optimized for the highest amount of coating hardness using the Design Of Experiment (DOE) method. The optimized deposition parameters were current density 23.7 A/dm2, duty cycle 75%, frequency equal to 188 Hz, temperature equal to 70ºC and 17.5 gr/l of H3PO3. The DOE prediction of hardness for the optimized coatings was between 700 and 750 the achieved micro-hardness was about 725.8 HV. It was obtained that an increase of the current density will improve micro-hardness, decreases P content and increase deposition rate. Also, the...

The Synthesis of Sialon Nano Particles by Sol- Gel Procedure and Investigation of Properties of its Erosion

, M.Sc. Thesis Sharif University of Technology Fathi, Hamed (Author) ; Nemati, Ali (Supervisor) ; Halali, Mohammad (Supervisor)

Abstract

Sialons are materials which crystallize in four elements system (Si-Al-O-N). These materials have been widely observed by researchers because of their suitable properties like: high toughness and strength in high temperatures, high resistance to corrosion and stability in thermal shock. Because of these properties,Sialons are anti erosion materials. In this research, by controling the situations, mullite has been synthesized by sol-gel procedure. Then the powder has been ground by ballmill for 12 hours and by spex for 30 minutes. Then the produced powder was mixed with distinct amount of graphite and nano silica and was nitrided in the furnace at 1500 ̊C and was heated for 5 hours. Also...

Production of Dermal Fillers with Particular Medical Purposes

, M.Sc. Thesis Sharif University of Technology Ranjbar Fathi, Hamed (Author) ; Abdekhodaie, Mohammad Jafar (Supervisor)

Abstract

Wrinkles on the skin are among the most common effects of aging, which are associated with a decrease in the concentration of fibroblast cells and the breakdown of collagen and elastin chains. Youthfulness and skin beauty are important attributes of nature that are directly linked to human self-confidence, attracting numerous candidates each year for skin rejuvenation and restoration. Over the years, several non-invasive methods have been introduced to address wrinkles and increase the volume of subcutaneous tissue, with subdermal fillers emerging as an effective and safe approach commonly used in aesthetic clinics. Commercial fillers are categorized based on factors such as the base...

Flexible Design of LNG Multi-Stream Heat Exchanger (Coldbox) with the Focus on Exergy Destruction and Part-load Operation

, M.Sc. Thesis Sharif University of Technology Fathi, Mohammad Sadegh (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Hosseini, Vahid (Supervisor)

Abstract

Natural gas liquefaction is a gas refrigeration technology, which enables the export of natural gas worldwide, in liquids formed and stored at very low temperatures. In this project, a plate-fin type of heat exchanger, which is used for liquefaction of natural gas (mainly methane) at very low temperatures, has been investigated. The most important and effective part of this gas refrigeration cycle is the cold box heat exchanger. The cold box consists of two or more floors in which some sorts of fins are installed in each floor. In this simulation, the three-sream heat exchanger is designed in such a way that the input temperature of the natural gas is about 200 K and the output is 145 K at a...

Analysis and Improvement of Intrusion Detection Methods in Data Network Routers

, M.Sc. Thesis Sharif University of Technology Jamshidi, Mohammad Ali (Author) ; Aref, Mohammad Reza (Supervisor) ; Pakravan, Mohammad Reza (Co-Advisor)

Abstract

High-quality online services demand reliable and fast packet delivery at the network layer. However, clear evidence documents the existence of compromised routers in the ISP and enterprise networks, threatening network availability and reliability. A compromised router can stealthily drop, modify, inject, or delay packets in the forwarding path to launch Denial-of-Service, surveillance, man-in-the-middle attacks, etc. So researches tried to create intrusion detection methods to identify adversarial routers and switches. To this end, data-plane fault localization (FL) aims to identify faulty links and is an effective means of achieving high network availability. FL protocols use...

Topological Defects in Confined Nematics by Planar Anchoring

, M.Sc. Thesis Sharif University of Technology Seyed Nejad, Reza (Author) ; Ejtehadi, Mohammad Reza (Supervisor) ; Mozaffari, Mohammad Reza (Supervisor)

Abstract

Confining nematic liquid crystal between two curved boundary conditions while the nematic molecules have a degenerate planar anchoring leads to complex and beautiful textures of molecular disparagement(defect) in the bulk and on the surfaces. Such the liquid crystal shells are made with double-emulsion techniques in microfluidic devices have provided applications for micro-scale colloidal linkers.In this work, we have numerically minimized the elastic energy in one-constant approximation in present of Fournier’s degenerate surface potential with finite element method. The nematic shell is confined between two spherical surfaces that we have studied the final energies and their related...