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sanati-baygi--mohammad-reza
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Design and Build of Small USVs by Capability of Swarm Control
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor)
Abstract
This research addresses the design, simulation, and experimental implementation of small intelligent Unmanned Surface Vehicles (USVs) for swarm-based operation and autonomous navigation. The primary objective is to establish an experimental framework for validating swarm guidance algorithms and assessing how theoretical control strategies transfer to physical vessels. In the theoretical phase, a catamaran dynamic model was developed to represent planar motion (surge, sway and yaw). Using this model, a leader–follower coordination scheme—adopted here as a swarm control strategy—was formulated to describe interactions between a leader and its followers under a set of representative scenarios....
Effect of the Chemical Coagulant and Oxidizer on the Membrane Fouling During the Treatment of Wastewater Using a Membrane Bioreactor
, M.Sc. Thesis Sharif University of Technology ; Moslemi, Mohammad Reza (Supervisor)
Abstract
Membrane bioreactor (MBR) is a combination of conventional activated sludge (CAS) and membrane filtration which owing to its advantages such as high quality effluent and low excess sludge production, has gained increasing application in wastewater treatment. The major drawback of a MBR is the membrane fouling that reduces the permeate flux, which in turn increases the overall operational costs due to high energy requirements. In existing study, the combination of sludge oxidation and coagulation/flocculation addition was investigated for mitigation of membrane fouling in a membrane bioreactor. Oxidation can facilitate sludge flocculation and hence improve the properties of mixed liquor. The...
New Results on Different Types of Visibility Problems
, Ph.D. Dissertation Sharif University of Technology ; Ghodsi, Mohammad (Supervisor)
Abstract
The study of visibility is at least 100 years old, when in 1913 Brunn proved a theorem about the kernel of a set. By now, visibility has become one of the most studied notions in computational geometry. The reasons are two-fold: 1) such problems arise naturally in areas where computational geometry tools and algorithms _nd applications including: computer graphics, robotics, motion planning, geographic information systems, computer games, computer-aided architecture, and pattern recognition; and where 2) their solutions are required, or serve as building blocks in the development of solutions to other problems, such as shortest paths or motion planning problems. Many natural problem...
Incremental Dynamic Analysis in Regular Concrete Structures with Seismic Base Isolators
, M.Sc. Thesis Sharif University of Technology ; khaloo, Alireza (Supervisor)
Abstract
Although the issue of separation is studied frequently in the last few decades, in presence of numerous parameters and unknown effects of earthquakes and soil condition, scientists confront with remarkable difficulties. It was supposed that performance of structures which are secluded from soil remains in the elastic region and doesn’t bear nonlinearity. But according to recent studies, scientist assert that nonlinear performance might be possible as a result of various soil condition and ingredients of earthquake(magnitude and frequency). General procedure for seismic improvements of structures includes increasing the strength and resistance, capability of structure to absorb energy and...
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 ; 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...
Numerical Study of Base Plates under Biaxial Bending
, M.Sc. Thesis Sharif University of Technology ; Khonsari, Vahid (Supervisor)
Abstract
Base plates as the connecting components of steel structures to their foundations, have a crucial role in the behavior of these structures. In order to limit the thickness of base plates hence their cost within reasonable values, various types of attachments (stiffeners) are normally added to them. In this project 6 different configurations, Models, for the base plate and its attachments were considered and studied through finite element analysis. Each Model was studied under the combination of biaxial moments and a range of compressive loads including 0, 0.05 P/Py, 0.10 P/Py and 0.15 P/Py, where Py is the plastic load of the column. The moment-rotation curves of all models under various...
Space/query-time tradeoff for computing the visibility polygon
, Article Computational Geometry: Theory and Applications ; Volume 46, Issue 3 , April , 2013 , Pages 371-381 ; 09257721 (ISSN) ; Ghodsi, M ; Sharif University of Technology
2013
Abstract
In this paper, we consider the problem of computing the visibility polygon (VP) of a query point q (or VP(q)) in a scene consisting of some obstacles with total complexity of n. We show that the combinatorial representation of VP(q) can be computed in logarithmic time by preprocessing the scene in O( n4logn) time and using O( n4) space. We can also report the actual VP(q) in additional O(|VP(q)|) time. As a main result of this paper, we will prove that we can have a tradeoff between the query time and the preprocessing time/space. In other words, we will show that using O(m) space, we can obtain O( n2log(m/n)/m) query time, where m is a parameter satisfying n2≤m≤ n4. For example, when m= n3,...
The Assessment of Joint's Rigidity Effect on the Nonlinear Dynamic Behaviour of Steel Frames with Semi-Rigid Connections
, M.Sc. Thesis Sharif University of Technology ; Mofid, Massoud (Supervisor)
Abstract
In this thesis project the effect of joint rigidity on the behavior of steel braced frames has been investigated. In order to carry out this study on the efficiency of semi-rigid connections, a series of 3-bay braced frames ranging from 6- to 20-story with extended end-plate and flush end-plate connections have been selected and designed. This study has been extended by evaluating the role of the mentioned connections on seismic performance of selected semi-rigid frames under seven famous earthquake records. Having taken a particular performance level, in this case, “life safety” the target displacement and also the lateral load pattern for each frame have been calculated. Then using a...
Analysis and Improvement of Intrusion Detection Methods in Data Network Routers
, M.Sc. Thesis Sharif University of Technology ; 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...
Comparing Performance of M.V, E.G.P and M.V.S Based on Genetic Algorithm in Iranian Capital Market
, M.Sc. Thesis Sharif University of Technology ; Bahramgiri, Mohsen (Supervisor)
Abstract
The portfolio selection problem is always one of the most important problems of finance and investments due to its great implication and vital role in financial institutions. Many of researches in this area are based on the mean-variance model, originally proposed by Markoitz. In the last two decades, however, researchers and investors have attracted to some new models that import some new factors other than mean and variance in the portfolio decision problem, such as different risk measures, etc. In this research we compare performances of mean-variance, Elton-Gruber-Padberg (EGP) and mean-variance-skewness based on genetic algorithm in Tehran Stock Exchange. Moreover, in order to find the...
Topological Defects in Confined Nematics by Planar Anchoring
, M.Sc. Thesis Sharif University of Technology ; 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...
Solving Symmetric Nonlinear Equations System Using BFGS Trust Region Quadratic Method
, M.Sc. Thesis Sharif University of Technology ; 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 ; 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 ; 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 ; 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 ; 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...
Optimization of Vehicle Routing Problem with Self-pickup-delivery and Option Delivery Locations
, Ph.D. Dissertation Sharif University of Technology ; Akbari Jokar, Mohammad Reza (Supervisor)
Abstract
With the increasing tendency of consumers to purchase from online stores and the remarkable growth of this industry in recent years, timely and cost-efficient delivery of goods to the final customer has become one of its major challenges. Accordingly, last-mile delivery has attracted significant attention from both researchers and practitioners. This study addresses a vehicle routing problem that considers customers’ ability to pick up their orders from selected centers and their possible presence at different locations within the planning horizon. This thesis aims to enhance customer satisfaction and reduce distribution costs by employing two innovative vehicle routing approaches. The first...
The combination of KMnO4 oxidation and polymeric flocculation for the mitigation of membrane fouling in a membrane bioreactor
, Article Separation and Purification Technology ; Volume 159 , 2016 , Pages 124-134 ; 13835866 (ISSN) ; Moslemi, M ; Mirzaei, S. H ; Sharif University of Technology
Elsevier
2016
Abstract
KMnO4 oxidation combined with polyelectrolyte (K530CF) flocculation was investigated to mitigate membrane fouling in a membrane bioreactor. The optimum dosages of chemical additives in order to enhance the removal of soluble microbial products (SMPs) were determined. This method was able to reduce the concentration of COD in the effluent to 57.1% and 51.1% lower than those in the experiments in the absence of chemical flocculants and in the presence of polyelectrolyte, respectively. NH3-N removal was improved by combining KMnO4 and K530CF. When KMnO4 was used along with polyelectrolyte, the zeta potential was neutralized to a greater extent which resulted in an improvement in the...
SH-wave Propagation in phononic Crystals of Periodic Nanostructures with Deformable Interfaces
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Shodja, Hossein (Supervisor)
Abstract
The aim of this study is to investigate the propagation of anti-plane shear waves in an elastic medium composed of periodic nanolayers (metamaterials) with deformable interfaces.Some of interesting properties of metamaterials are band-gaps and negative refraction angle.In nanolayered mediums the effect of interface becomes significant and classical continuum theory is not sufficient individualy. In this research by introducing 4 interface parameters and adding some equations to classical continuum theory, the possibilty of discontinuity of traction and displacement across the interface is provided and the effect of interface is considered. Then, a functional representing the energy of the...
Design and Fabrication of Advanced Electrode Materials Based on Metal-organic Frameworks and Double Layered Hydroxides Using Hollow Copper Hydroxide Nanotubes Scaffold; Application to Nonenzymatic Glucose Sensor
, M.Sc. Thesis Sharif University of Technology ; Shahrokhian, Saeed (Supervisor)
Abstract
One of the remarkable subject in advanced electrochemistry is, design and architecting new advanced materials with new electrochemical capabilities. One of the notable capabilities is electrocatalysis. Extensive researches are carrying out into the design and preparation of electrocatalyst materials to take advantage of these materials in fabrication of electrochemical sensors and storage/conversion devices. In this field nonoporous materials attracted a lot of attentions due to their unique features. In order to make use of the nanoporous materials as the electrocatalysts, these materials must be fabricated into continuous supported thin films on the electrode surface, which is the...