Seismic Response of “Karroon III” DAM to Non-Uniform Ground Motions

, M.Sc. Thesis Sharif University of Technology Pouya, Mohammad Reza (Author) ; Ghaemian, Mohsen (Supervisor)

Abstract

Usually in analysis of arch dams, applied seismic motions on dam-foundation interface are assumed to be uniform. This is while that recorded motions show non-uniform accelerations in dam-foundation interface. Analyzing of the dam under this non-uniform accelerations we can find the importance of this assumption in analysis of arch dams. Two earthquakes were excited “KAROON III” dam at 20.11.2007 and 21.11.2007. The respective motions were recorded by the array of accelerometers that has been installed on the dam. The recorded motions, indicated non-uniformity of excitations in accelerometers were installed near the dam-foundation interface. Therefore this data provided an opportunity to...

Autonomous runway alignment of fixed-wing unmanned aerial vehicles in landing phase

, Article 5th International Conference on Autonomic and Autonomous Systems, ICAS 2009, Valencia, 20 April 2009 through 25 April 2009 ; 2009 , Pages 208-213 ; 9780769535845 (ISBN) Pouya, S ; Saghafi, F ; Sharif University of Technology

2009

Abstract

In this paper, the development of a controller for autonomous lateral alignment of fixed-wing Unmanned Aerial Vehicles (UAVs) with runway centerline in landing phase is presented. Fuzzy Logic Control (FLC) is used in order to enable the vehicle to mimic the decision making procedure that a pilot follow in the same situation. Also, for longitudinal motion controller design for the UAV to follow a pre-defined trajectory, the pole-placement technique is used. It is assumed that the runway relative position and orientation are provided by a built in vision system and its associated image processing unit. The performance of the controller in the presence of the Gaussian noises is investigated by...

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...

Improved optimal control technique for control of parallel three- phase inverters

, Article 2009 International Conference on Electric Power and Energy Conversion Systems, EPECS 2009, Sharjah, 10 November 2009 through 12 November 2009 ; 2009 ; 9789948427155 (ISBN) pouya, H. R. N ; Mokhtari, H ; Sharif University of Technology

2009

Abstract

This paper proposes a high performance voltage tracking and current sharing among parallel connected inverters by applying optimal control and minimizing the cost function. The control system forces the voltage of load to track the voltage reference, and the current of all inverters becomes equal. Therefore, both current sharing and voltage tracking are obtained. In addition, the smallest input energy and simplicity in control circuit are the other advantages of the suggested method. To show the performance of the proposed control scheme, the simulations with two-modular practical systems are performed and the results are provided. The results indicate that the control objectives are...

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...

The effect of non-uniformity in ground motions on the seismic response of arch dams

, Article SN Applied Sciences ; Volume 3, Issue 3 , 2021 ; 25233971 (ISSN) Pouya, M. R ; Sohrabi Gilani, M ; Ghaemian, M ; Sharif University of Technology

Springer Nature 2021

Abstract

Recorded ground accelerations at various locations of Karun III Dam during November 20, 2007, were recorded by an array of accelerometers located on the dam. In terms of amplitude and phase, these accelerations show non-uniformities in different elevations. In this paper, the effect of these non-uniform ground motions on the seismic response of the dam taking dam-reservoir-foundation interaction into account is investigated. The EACD-3D-2008 finite element program and ABAQUS Software are used for carrying out the seismic analyses. For this purpose, time histories of the earthquake accelerations are interpolated at nodal points located on the dam foundation interface. The analysis has been...

Thermal analysis of RCC dams during construction considering different ambient boundary conditions at the upstream and downstream faces

, Article Journal of Civil Structural Health Monitoring ; Volume 12, Issue 3 , 2022 , Pages 487-500 ; 21905452 (ISSN) Pouya, M. R ; Sohrabi Gilani, M ; Ghaemian, M ; Sharif University of Technology

Springer Science and Business Media Deutschland GmbH 2022

Abstract

Thermal analysis of Roller Compacted Concrete (RCC) dams is generally carried out considering identical ambient boundary conditions at upstream and downstream faces. For the case of Shahri-Kor Dam (an RCC dam with a height of 57 m), recorded thermal data depicts a considerable difference between upstream and downstream ambient temperatures, especially during cold months. This paper investigates how taking this difference into account can affect the thermal response of the dam. For this purpose, two thermal analyses are carried out with and without consideration of these different ambient boundary conditions (DABC). Consequently, the computed temperatures at representative points are compared...

Design of a Control System Based on the Permanent Magnet for Control of a Magnetic Catheter

, M.Sc. Thesis Sharif University of Technology Hatami Pouya, Mohammad (Author) ; Nejat Pishkenari, Hossein (Supervisor)

Abstract

Currently, the use of robots and microrobots in medical applications has significantly increased due to their extensive and unique capabilities. One such application involves the utilization of magnetic continuum robots controlled by an external magnetic field in minimally invasive surgeries. This research focuses on discussing methods for effectively controlling magnetic-continuum robots and applying external magnetic fields. Two primary methods for applying the external magnetic field are explored: the use of electromagnetic coils and permanent magnets. Based on these methods, systems for applying the field and controlling the magnetic continuum robot have been constructed and...

Solving Symmetric Nonlinear Equations System Using BFGS Trust Region Quadratic Method

, M.Sc. Thesis Sharif University of Technology Salimi, Samira (Author) ; Razvan, Mohammad Reza (Supervisor) ; Peyghami, Mohammad Reza (Supervisor)

Effect of the Geometry of Colloidal Particles on Nematic Liquid Crystals

, Ph.D. Dissertation Sharif University of Technology Hashemi, Masoumeh (Author) ; Ejtehadi, Mohammad Reza (Supervisor) ; Mozaffari, Mohammad Reza (Co-Advisor)

Abstract

A liquid crystal is a state of matter composed of highly anisotropic building blocks. When liquid crystals are exposed to surfaces with given shapes and anchoring conditions, the orientation of their molecules gets spatially disordered and topological defects may form in the system. The interplay between liquid crystals and the geometry and topology of the colloidal particles has motivated extensive recent studies.In this thesis, we present the numerical modeling results for two faceted colloidal particles in a thermotropic nematic liquid crystal. To obtain the equilibrium nematic field with a finiteelement method, we numerically minimize the free energy of the system that based on the...

Design and Implementation of 2.5 Gbps Circuit Switching Fabric

, M.Sc. Thesis Sharif University of Technology Jahani, Sohrab (Author) ; Pakravan, Mohammad Reza (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)

Abstract

Providing high bandwidth network infrastructures for ever increasing need of data transport is of great importance. The underling infrastructure for many communication services such as GSM/3G/4G mobile networks and Internet services is Synchronous Digital Hierarchy (SDH) optical transport systems. SDH are standardized protocols that multiplex multiple lower rate digital bit streams, such as E1 and Ethernet, and transfer them synchronously over optical fiber using lasers or LEDs. In addition to high data transfer rates, flexible network management and protection mechanisms have great importance, hence are part of SDH standards. In order to obtain flexible network architecture and protected...

Preserving Privacy in Smart Grid

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

Abstract

Development of Smart Grid and deployment of smart meters in large scale has raised a lot of concerns regarding customers’ privacy. Consequently, several schemes have been proposed to overcome the above mentioned issue. These schemes mainly rely on data aggregation as a method of protecting users’ privacy from the grid operators. However, the main problem with most of these schemes is the fact that they require a large amount of processing power at the meter side. This, together with the fact that smart meters don’t usually have a powerful processor, can cause the unavailability of smart meter data at the required time for operators of the grid, and at the same time disables smart meters from...

Improvement of Routing Security in Ad Hoc Networks Against Several Attacks

, M.Sc. Thesis Sharif University of Technology Sedghi, Hanie (Author) ; Aref, Mohammad Reza (Supervisor) ; Pakravan, Mohammad Reza (Supervisor)

Abstract

Secure routing is a major key to service maintenance in wireless ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. Wormhole attack is one of the most severe active attacks to mobile ad hoc networks. Noting 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...

Solving Nonlinear Systems of Mixed Iqualities and Inequalities Via Trust Region Quadratic Methods

, M.Sc. Thesis Sharif University of Technology Ghasemi, Shojaeddin (Author) ; Razvan, Mohammad Reza (Supervisor) ; Payghami, Mohammad Reza (Supervisor)

Jamming Resilient Algorithms for Rendezvous in Cognitive Radio Networks

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

Abstract

Dynamic spectrum access with the aid of cognitive radio (CR) technology is a viable solution to spectrum scarcity. There are many military and emergency applications that require the use of cognitive radio ad-hoc networks (CRAHNs). In these net- works, nodes must ﬁrst ﬁnd each other in a wide spectrum and then exchange their desired data. The process of ﬁnding each other in a multichannel environment is a challenging task and is usually known as rendezvous. Since rendezvous is the ﬁrst step in communication, disrupting will disable the nodes from establishing proper communication sessions. That results in a drastic degrade in the performance of the network. Therefore, it is important to...

Numerical Study of Spray Impingement to Solid Wall

, M.Sc. Thesis Sharif University of Technology Abbasi Chenari, Fatemeh (Author) ; Morad, Mohammad Reza (Supervisor) ; Jahannama, Mohammad Reza (Co-Supervisor)

Abstract

Spray-wall impingement is one of the phenomenon that associated in different subject such as spray cooling, combustion chamber and gas turbine. With the impingement of spray to the wall, liquid film begins to form. Wall film characteristics is still an important subject to study. Due to the various stages of liquid film formation from injection of spray till spray-wall impingement, the investigation of this phenomenon is far more complicated. This paper is meant to provide detailed data on spray-wall impingement and wall film formation physics with the help of computational analysis of OpenFOAM . A Lagrangian-Eulerian method based on discrete phase model (DPM) was employed to model...

Assessing and Improving Algorithms to Control the Propagation of Light through Scattering Media

, M.Sc. Thesis Sharif University of Technology Fayyaz, Zahra (Author) ; Rahimitabar, Mohammad Reza (Supervisor) ; Nasiriavanaki, Mohammad Reza (Supervisor)

Abstract

Light propagation through turbid media, such as biological tissues, experience scattering due to inhomogeneous distribution of refractive indices of their microscopic structure. Scattering and diffusion of light not only limit many optical imaging techniques, but are also big challenges for telecommunication, spectroscopy, and other optical techniques. Recently many new imaging methods are developed that work in strongly scattering media such as optical coherence tomography, diffusion tomography, and laser speckle velocimetry. In this thesis, we have studied how wavefront shaping techniques can tackle the problem of scattering. By spatially shaping the wavefront of the incident beam, using...

Photocatalytic mechanism of action of apatite-coated Ag=AgBr=TiO 2 on phenol and Escherichia coli and Bacillus subtilis bacteria under various conditions

, Article Progress in Reaction Kinetics and Mechanism ; Vol. 1 , Vol.36 (1) , 2011 , pp.38-52 Elahifard, M. R. (Mohammad Reza) ; Gholami, M. R. (Mohammad Reza) ; Rahimnejad, S. (Sara) ; Pourbaba, R. (Reza) ; Haghighi, S.(Saeed) ; Sharif University Of Technology

2011

Abstract

Multi-component photocatalysts based on apatite-coated Ag/AgBr/TiO(2) were prepared by the deposition method. The effects of various kinds of apatites, with hydroxyl and fluoro substituents, on photocatalytic activity were investigated. The antibacterial processes in the dark, and under visible light, on two types of bacteria indicate that the multi-composites can inhibit the growth of bacteria by two different mechanisms. TEM images and optical microscopic data demonstrate that by attaching the nanosize catalyst to the outer membrane of the cell, the bacteria could not derive nourishment from surrounding media, i.e. this component acts as bacteria-static. The mechanism for deactivation of...

Solvatochromic Probes Absorbance Behavior in Mixtures of 2-Hydroxy ethyl ammonium formate with methanol, ethylene glycol and glycerol

, Article Journal of Solution Chemistry ; Volume 39, Issue 10 , October , 2010 , pp 1509-1519 Salari, H. (Hadi) ; Harifi-Mood, A. R. (Ali Reza) ; Elahifard, M. R. (Mohammad Reza) ; Gholami, M. R. (Mohammad Reza) ; Sharif University of Technology

2010

Abstract

Solute-solvent and solvent-solvent interactions were investigated for binary mixtures of an ionic liquid (IL) 2-hydroxy ethylammonium formate as with methanol, ethylene glycol and glycerol. The physicochemical properties of the solvent mixtures at 25 °C, over the whole range of mole fractions, were determined using solvatochromic probes. High normal polarity ( ENT ) in the alcohol-rich region confirms solute-solvent interactions in this medium. Dipolarity/polarizability (π ∗) show a different trend to ENT with a positive deviation from ideal behavior in IL-glycerol mixtures. However, these deviations for other solvent mixtures are insignificant. Contrary to what is observed for ENT and π ∗,...