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abed-niari--saeed
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CFD Simulation and Analysis of Heat Pipe Heat Exchanger Radiator
, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
Due to the development of heat pipes in different industries and special characteristics of heat pipes, in this study, it has been tried using computational fluid dynamics (CFD) method to simulate a heat pipe heat exchanger that can be a replacement for the normal radiator. The experimental model of this heat exchanger has been tested at past studies and the numerical simulation of the heat exchanger will analyze at present study. The use of heat pipe in the car radiator has many advantages such as reducing fluid pressure drop through the heat exchanger, high reliability due to the particular structure of the heat exchanger (individual performance of each heat pipe) and improving heat...
A new achievable rate for a stochastic two relay network with no interference
, Article 2008 42nd Asilomar Conference on Signals, Systems and Computers, ASILOMAR 2008, Pacific Grove, CA, 26 October 2008 through 29 October 2008 ; June , 2008 , Pages 909-913 ; 10586393 (ISSN); 9781424429417 (ISBN) ; Sharif University of Technology
2008
Abstract
Gastpar and Vetterli named the adhoc networks with one randomly selected source-destination pair as relay networks and they suggested using arbitrary network coding in order to increase the overall efficiency Here, the relay network is investigated with two relays and no interference and a new achievable rate is obtained using a new network coding (decodeand-broadcast). The obtained achievable rate (i) gives the lower bound for the general relay channel, obtained by Cover and El Gamal, but with slight difference due to no interference assumption at the receiver (ii) includes the one relay rates of a two-level relay channel studied by Gupta and Kumar using point to point coding, (iii)...
Verification of OSPF vulnerabilities by colored petri net
, Article SIN 2013 - Proceedings of the 6th International Conference on Security of Information and Networks ; November , 2013 , Pages 102-109 ; 9781450324984 (ISBN) ; Jahangir, A. H ; Sharif University of Technology
2013
Abstract
Routers and routing protocols are critical parts of a network infrastructure. OSPF is one of the most important routing protocols, and therefore its vulnerabilities can be very destructive. This makes its security analysis critical. There are many reported and potential vulnerabilities in OSPF protocol. Considering the complexity and the ambiguity of its description in RFC 2328, it is very valuable to design a formal model of the protocol and analyze the vulnerabilities of its critical parts. In this paper, some challenging parts of OSPF protocol along with attack scenarios are modeled by means of Colored Petri Net in CPN Tools environment. Then, the reported vulnerabilities are analyzed by...
Modeling Multi-path Covering Routing Problem
, M.Sc. Thesis Sharif University of Technology ; Koorosh, Eshghi (Supervisor)
Abstract
The location problem is one of the main topics at the strategic level. This problem is investigated along with many areas such as network design and path covering problems. Routing between source and destination nodes is done in such a way that maximizes traffic coverage and reduces costs as much as possible. Routing problems are considered in goods distribution areas and urban transit systems. Goods distribution from set of cross-docks can help to reduce costs and improve resource efficiency. So, this topic is considered in this research and a suitable model is proposed. Defining and developing of the road and rail transportation networks are main topics in urban traffic management which...
Analysis and Evaluation of Router Security Based on a Routing Protocol
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor)
Abstract
The importance of routers in information transfer among networks is critical. Thus, vulnerabilities and security deficiencies in routers and the related services like routing protocols can be destructive not only for some hosts, but also for the whole network. Hence, it is necessary that 1) vulnerabilities related to the routers and their services be evaluated and analyzed, and 2) the functional aspects of routers related to the vulnerabilities be formally modeled and analyzed. In this thesis, we present a method for the evaluation and the analysis of OSPF routing protocol from the security point of view. First, reported vulnerabilities on the OSPF are collected and evaluated by a...
Topology analysis of manufacturing service supply–demand hyper-network considering QoS properties in the cloud manufacturing system
, Article Robotics and Computer-Integrated Manufacturing ; Volume 72 , 2021 ; 07365845 (ISSN) ; Eshgi, K ; Fatahi Valilai, O ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Cloud Manufacturing (CMfg), a new manufacturing paradigm, enables an opportunity for manufacturing enterprises to respond to a wide variety of demands. The CMfg concept integrates the distributed resources and capacities in a shared economy, transfers them to the virtual manufacturing services with various quality of service (QoS) properties. These services are invoked to collaborate in producing customized demands with specific functional and non-functional properties. The operational perspective of the service-demand matching problem is considered more in the literature; however, it is a challenging problem in the CMfg ecosystem. This paper evaluates the service-demand matching problem...
Adaptive capacity management in cloud manufacturing hyper-network platform: Case of COVID-19 equipment production
, Article International Journal of Management Science and Engineering Management ; Volume 17, Issue 4 , 2022 , Pages 239-258 ; 17509653 (ISSN) ; Eshghi, K ; Fatahi Valilai, O ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
Cloud Manufacturing (CMfg) is a service-oriented manufacturing (SOM) paradigm that provides a dynamic, scalable, and virtualized working ecosystem. The CMfg collaborative structure can be modeled as a hyper-network-based service-demand matching architecture. It is enriched with quality of service (QoS) characteristics to produce customized products in a stable and reliable network. This stability should be considered in the overall manufacturing network mechanism. This paper has provided adaptive strategies utilizing available resources and capacities to enhance the system’s stability and reliability against the unexpected events. The capabilities of the enhanced framework are utilized to...
Capacity of Almost General Relay Channel and Aref Network with Random Links
, Ph.D. Dissertation Sharif University of Technology ; Aref, Mohammad Reza (Supervisor)
Abstract
First, we review in an appropriate way the researches regarding building blocks of a wireless network (Shannon channel, multiple access channel, broadcast channel, interference channel, relay channel) and then: • We consider two cases for a relay and describe the essential role of the relay with three Markovity conditions; define Almost General Relay Channel with Decode-And-Forward (AGRCDAF) strategy and determine its capacity. Then, we prove that our capacity theorem not only includes all known capacity theorems as its special cases but also potentially is applicable to other relay channels and is validated by its consistency with previous results related to special cases of broadcast and...
The contagion effects of global financial crisis on Tehran Stock Exchange
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Haddad, Gholamreza (Supervisor)
Abstract
US 2008 financial crisis, spread across the international stock markets in the second half of the year 2008. The crisis decreased the returns and increased the volatilities of almost all of the stock indices, however, its effects on Iran’s stock markets were unexplored. Financial limitations create an exclusive situation in Iran’s stock market. Using weekly data on the stock indices from July 2006 through August 2009, this study aims to exam in the contagion effects of the global financial crisis through the main indices such as S&P500 and FTSE100 on Tehran Stock Exchange indices: industrial and financial intermediary indices and The First and the Second indices of Tehran’s Stock Exchange....
Multiuser detector for airborne co-located multiple input/multiple output radar using compressive measurements
, Article IET Radar, Sonar and Navigation ; Volume 11, Issue 2 , 2017 , Pages 260-268 ; 17518784 (ISSN) ; Salehi, J. A ; Hariri, A ; Sharif University of Technology
Institution of Engineering and Technology
2017
Abstract
This study presents and analyses a novel joint detection and parameters estimation of multiple targets using a co-located multiple input/multiple output radar with moving platform, in the presence of clutter and background noise. A notable feature of the proposed approach is that clutter cancellation is independent of received data. Moreover, to decrease the computational load, the authors propose to perform the target detection and parameters estimation by directly processing on the compressive measurements as opposed to Nyquist samples. © The Institution of Engineering and Technology
Developing Mathematical Model for Service-Demand Matching in Cloud Manufacturing Network
, Ph.D. Dissertation Sharif University of Technology ; Eshghi, Kourosh (Supervisor) ; Fatahi Valilai, Omid (Supervisor)
Abstract
Cloud Manufacturing (CMfg) is a service-oriented manufacturing (SOM) paradigm that provides a dynamic, scalable, and virtualized working ecosystem. The CMfg collaborative structure can be modeled as a hyper-network-based service-demand matching architecture. It is enriched with quality of service (QoS) characteristics to produce customized products in a stable and reliable network. This stability should be considered in the overall manufacturing network mechanism. This Thesis has developed a multi-dimentional model and improved it by providing absorptive and adaptive strategies utilizing available resources and capacities to enhance the system’s stability and reliability against the...
Discrete scale invariance and its logarithmic extension
, Article Nuclear Physics B ; Volume 655, Issue 3 , 2003 , Pages 342-352 ; 05503213 (ISSN) ; Aghamohammadi, A ; Khorrami, M ; Rahimi Tabar, M. R ; Sharif University of Technology
Elsevier
2003
Abstract
It is known that discrete scale invariance leads to log-periodic corrections to scaling. We investigate the correlations of a system with discrete scale symmetry, discuss in detail possible extension of this symmetry such as translation and inversion, and find general forms for correlation functions. © 2003 Published by Elsevier Science B.V
A new approach to model sensitivity of graphene-based gas sensors
, Article Semiconductor Science and Technology ; Volume 30, Issue 4 , March , 2015 ; 02681242 (ISSN) ; Ismail, R ; Naraghi, B ; Taheri Abed, S ; Kavosi, D ; Fotovatikhah, F ; Sharif University of Technology
Institute of Physics Publishing
2015
Abstract
Carbon-based sensors are attractive because of their excellent sensing capability. In this paper, we propose a new approach to analytically model the sensitivity of these devices based on graphene. The model relies on the surface potential and current of the device. For the first time, we included ionization in the modelling and examined the importance of this effect. In order to validate the model, the results are compared with experimental data from a fabricated device
Performance of three-level spectrally encoded spreadtime CDMA in the presence of multiple interferences [electronic resource]
, Article IET Communications ; July 2011, Volume 5, Issue 10, P. 1328-1335 ; Mashhadi, Saeed ; Salehi, J. A ; Sharif University of Technology
Abstract
In this study the authors present an in-depth study, analysis and discussion on maximum likelihood (ML)-based receiver for a typical spectrally encoded spread-time CDMA in the presence of multiple narrowband interference (NBI) signals in an additive white Gaussian noise channel. Furthermore, the authors demonstrate that by combining useful properties of ML-based receiver and three-level codes, that is, codes with values of -1, 0, +1, the authors can introduce a new strategy in which superior performance with respect to previous receiver structure based on two-level codes, that is, codes with values of -1, +1, can be attained. With the help of an example, the authors drive, first, the...
Development of an esco risk assessment model as a decision-making tool for the energy savings certificates market regulator: a case study
, Article Applied Sciences (Switzerland) ; Volume 10, Issue 7 , 2020 ; Hatami, M ; Rahgozar, P ; Shirkhanloo, S ; Abed, S ; Kamalzadeh, H ; Flood, I ; Sharif University of Technology
MDPI AG
2020
Abstract
This article is focused on developing an Energy Service Company (ESCO) risk assessment model for use by energy savings certificates (ESC) market regulators. This model enables market regulators to determine the appropriate point in time for ESCOs to sell their certificates with the aim of minimizing risk as well as maximizing economic gain yet remain motivated for reducing the cost of energy efficiency technologies. To this end, the interactions between an ESCO and other parties (such as suppliers) in the market in addition to the principles of the energy efficiency performance contract are taken into consideration. Then, appropriate probability distributions have been fitted to the...
Use of Bio-Cementation for Reducing Land Subsidence
, M.Sc. Thesis Sharif University of Technology ; Khosravi, Ali (Supervisor) ; Pak, Ali (Supervisor) ; Ghobadi Nejad, Zahra ($item.subfieldsMap.e)
Abstract
Land subsidence is a gradual settling or sudden sinking of the land surface from changes that take place underground. There are different causes of land subsidence; most notably, groundwater overdraft and severe weather conditions. Subsidence of the land surface due to ground water overdraft is caused by an increase in the intergranular pressure in unconsolidated aquifers, which results in a loss of buoyancy of solid particles in the zone dewatered by the falling water table and accordingly compaction of the aquifer. In this study, an experimental approach was developed to examine applicability of Microbially induced carbonate precipitation (MICP) for land subsidence control under...
Investigation of Multiphase Flow in Oil Wells (with Focus on Two Phase Flow), Flow Pattern Recognition and Modeling
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor) ; Jamshidi, Saeed (Supervisor)
Abstract
The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In oil and gas, production engineers often face a situation in which more than one phase is flowing through the producers. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between...
Casing Design Optimization Considering Drilling and Production Conditions
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Saeed (Supervisor) ; Shad, Saeed (Supervisor)
Abstract
Casing design is one of the most expensive parts in the drilling of oil wells, and any cost reduction with the basic design of these casing strings will significantly reduce the total cost of the operation. In recent years, occurring scenarios-based casing design has become popular; Because in many cases, it eliminates non-occurring scenarios such as gas kick and saves on drilling costs. In this study, we have tried to investigate all scenarios that may occur during the lifetime of the well, whether drilling or production, and for each well, based on its own field information, possible scenarios for each casing part are selected separately and the applying loads are calculated. For this...
PRI (Palm Rotation Indicator): a metric for postural stability in dynamic nonprehensile manipulation [electronic resource]
, Article Journal of MECHANIKA ; 2012, Vol. 18, No. 4, pp. 461-466 ; Meghdar, Ali ; Sohrabpour, Saeed ; Sharif University of Technology
Abstract
In this study, we discuss the postural stability of a nonprehensile manipulation problem, which deals with multibody objects. As a metric for postural stability, we define PRI. Then, the system is posturally stable, if PRI is inside the convex hull of the object-manipulator contact surface. We then discuss that dynamic biped locomotion is a special case of dynamic nonprehensile manipulation in all aspects; we prove that ZMP (zero-moment point) and FRI (zoot rotation indicator) are special cases of PRI (palm rotation indicator). Simulations and experiments corresponding to simple examples support the results