Vision-based 3d Object Recognition

, M.Sc. Thesis Sharif University of Technology Forghani, Hossein (Author) ; Kasaei, Shohreh (Supervisor)

Abstract

Object recognition is a field of image processing with the purpose of object detection and determining its pose. There was a wide research of object recognition using 2d information. These methods are less efficient due to their sensitivity to view and scale. Today with development of 3d technology, 3d reconstruction of objects has been eased, thus there is a new trend of 3d methods. 3d object recognition uses 3d data and model to recognize objects more efficiently in different views and in occlusion and clutter. The related works are classified in three category of view-based, feature matching, and classification. In this research we attempted to improve one of the best feature matching...

A Secure and Efficient Digital Signature Based on Polar Codes

, M.Sc. Thesis Sharif University of Technology Forghani, Pouyan (Author) ; Aref, Mohammad Reza (Supervisor)

Abstract

Regarding to the emergence of quantum computers and advances in the large scale implementation of them, exploiting hard problems of coding theory is of great importance.This family of problems, like those of lattices, has an acceptable resistance against classic and quantum attacks. Thus, they can be replaced with hard problems in number theory and algebra. Increasing dominance of cyberspace made us highly dependent to it. Consequently, preparing tools and methods to mitigate future threats is necessary. Digital signatures constitute an important family of cryptographic primitives. Code-based digital signatures are mostly suffering from two main drawbacks: large public key and long time of...

A new efficient approach to search for all multi-state minimal cuts

, Article IEEE Transactions on Reliability ; Volume 63, Issue 1 , March , 2014 , Pages 154-166 Forghani Elahabad, M ; Mahdavi Amiri, N ; Sharif University of Technology

2014

Abstract

There are several exact or approximating approaches that apply {m d}-MinCuts (d-MCs) to compute multistate two-Terminal reliability. Searching for and determining d-MCs in a stochastic-flow network are important for computing system reliability. Here, by investigating the existing methods and using our new results, an efficient algorithm is proposed to find all the d-MCs. The complexity of the new algorithm illustrates its efficiency in comparison with other existing algorithms. Two examples are worked out to show how the algorithm determines all the d -MCs in a network flow with unreliable nodes, and in a network flow of moderate size. Moreover, using the d-MCs found by the algorithm, the...

An efficient algorithm for the multi-state two separate minimal paths reliability problem with budget constraint

, Article Reliability Engineering and System Safety ; Volume 142 , October , 2015 , Pages 472-481 ; 09518320 (ISSN) Forghani Elahabad, M ; Mahdavi Amiri, N ; Sharif University of Technology

Elsevier Ltd 2015

Abstract

Abstract Several researchers have worked on transmitting a given amount of flow through a network flow within fastest possible time, allowing flow to be transmitted through one or more paths. Extending this problem to the system reliability problem, the quickest path reliability problem has been introduced. The problem evaluates the probability of transmitting some given amount of flow from a source node to a sink node through a single minimal path in a stochastic-flow network within some specified units of time. Later, the problem has been extended to allow flow to be transmitted through two or more separate minimal paths (SMPs). Here, we consider the problem of sending flow through two...

A new algorithm for generating all minimal vectors for the q SMPs reliability problem with time and budget constraints

, Article IEEE Transactions on Reliability ; Volume 65, Issue 2 , 2016 , Pages 828-842 ; 00189529 (ISSN) Forghani Elahabad, M ; Mahdavi Amiri, N ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2016

Abstract

The quickest path reliability problem evaluates the probability of transmitting some given units of flow from a source node to a sink node through a single minimal path in a stochastic-flow network within some specified units of time. This problem has been recently extended to the case of transmitting flow through q separate minimal paths (SMPs) simultaneously within a budget constraint. Here, we propose a new algorithm to solve such problems. The algorithm finds all the minimal vectors for which a given demand level d units of flow can be transmitted through q SMPs from a source node to a sink node satisfying some given time and budget limits. In our proposed algorithm, a special...

An improved algorithm for finding all upper boundary points in a stochastic-flow network

, Article Applied Mathematical Modelling ; Volume 40, Issue 4 , 2016 , Pages 3221-3229 ; 0307904X (ISSN) Forghani elahabad, M ; Mahdavi Amiri, N ; Sharif University of Technology

Elsevier Inc 2016

Abstract

The d-MinCut (d-MC) problem has been extensively studied in the past decades and various algorithms have been proposed. The existing algorithms often consist of two general stages, finding all the d-MC candidates and testing each candidate for being a d-MC. To find all the d-MC candidates, a system of equations and inequalities should be solved. Here, we propose a novel efficient algorithm to solve the system. Then, using our new results, an improved algorithm is proposed for the d-MC problem. Computing its complexity, we show the proposed algorithm to be more efficient than the other existing algorithms with respect to the number of minimal cuts. A medium-size network example is worked...

Application of Axiomatic Design Theory in Cloud-Based Segmented Production Systems

, M.Sc. Thesis Sharif University of Technology Forghani Dehnavi, Mohammad (Author) ; Houshmand, Mahmoud (Supervisor)

Abstract

Designing and evaluating the segmented production structures of the production system due to the variety of production systems is one of the important issues that have been considered in recent decade. In this research, the paradigm of designing a segmented production system has been studied to increase the adaptation of the organizational structure of production systems to changing and diverse behavior of the market as well as to increase the responsiveness to demand in the organization. The segmented production system provides production units to small, flexible and decentralized production units. The segmentation process used in this research uses an axiomatic design structure. The...

PolarSig: An efficient digital signature based on polar codes

, Article IET Communications ; Volume 14, Issue 17 , 2020 , Pages 2889-2897 Forghani, P ; KoochakShooshtari, M ; Aref, M. R ; Sharif University of Technology

Institution of Engineering and Technology 2020

Abstract

Code-based digital signatures suffer from two main drawbacks: Large public key size and slow signature generation. Large public key size is inherent in almost all the code-based cryptosystems and other post-quantum alternatives; however, slow signature generation is due to their specific structure. Most of the current code-based signature schemes are constructed based on Courtois, Finiasz, and Sendrier (CFS) signature. CFS uses a counter to produce decodable syndromes or the complete decoding technique that imposes some extra computational cost to the signing algorithm for many choices of codes. In this study, the authors propose an efficient digital signature, PolarSig, which can reduce...

Price Forecasting for Short-Term Trading in the Coin Future Market

, M.Sc. Thesis Sharif University of Technology Forghani Saeedabadi, Mojtaba (Author) ; Kianfar, Farhad (Supervisor)

Abstract

Gold Coin Futures Market by contract delivery month of Dey, in 1387 as part of the capital market in Iran Mercantile Exchange started its activities. Each transaction in this market includes ten coins all gold (tamam bahar). Nowadays We have three symbols on each of the next three months are traded in an active market. In this market, any natural or legal person giving the guarantee fund with any of the agencies approved by the Stock Organization and in the terms of seller or buyer begin their trading. For transactions in order to succeed, we need to predict the rise or fall of prices to be a buyer in the rises and be seller in the falls. With considering the performance of Neural Networks...

A Process Model for Software Product line Engineering Based on the Model Driven Architecture

, M.Sc. Thesis Sharif University of Technology Forghani, Hadi (Author) ; Mirian Hosseinabadi, Hassan (Supervisor)

Abstract

Software development process is a base ground for all software activities and ensures all aspects of the software. No quality is guaranteed without a definite process. Model-Driven Software Development process proposes an industrial method for software companies to produce the required software through model(s) and tools. On the other hand, Software Product Line imposes a set of frameworks and principles. As a result a tangible decrement of development time and cost along with an increment of quality is achieved. Mixing both processes creates a stronger industrial process in order to decrease the development time and cost. In this thesis, through a survey on both of the processes and related...

An MP-based approximation algorithm on reliability evaluation of multistate flow networks

, Article Reliability Engineering and System Safety ; Volume 191 , 2019 ; 09518320 (ISSN) Forghani Elahabad, M ; Kagan, N ; Mahdavi Amiri, N ; Sharif University of Technology

Elsevier Ltd 2019

Abstract

In recent decades, multistate two-terminal reliability problem has attracted several researchers, and accordingly many exact and approximation approaches have been proposed in the literature in terms of minimal cuts (MCs) or minimal paths (MPs) to address this problem. Here, an MP-based approximation approach is developed based on exact algorithms. With all the MPs at hand, the approach rearranges the MPs ascendingly with respect to their lengths and then sets the flow on some MPs to be zero which turns to reduce the computing cost in solving the problem. We provide the complexity results, and by employing some benchmarks and one thousand randomly generated networks illustrate that not only...

On multi-state two separate minimal paths reliability problem with time and budget constraints

, Article International Journal of Operational Research ; Volume 37, Issue 4 , 2020 , Pages 479-490 Forghani Elahabad, M ; Mahdavi Amiri, N ; Kagan, N ; Sharif University of Technology

Inderscience Publishers 2020

Abstract

In a stochastic-flow network, a (d, T, b, P1, P2)-MP is a system state vector for which d units of flow can be transmitted through two separate minimal paths (SMPs) P1 and P2 simultaneously from a source node to a sink node satisfying time and budget limitations T and b, respectively. Problem of determining all the (d, T, b, P1, P2)-MPs, termed as the (d, T, b, P1, P2)-MP problem, has been attractive in reliability theory. Here, some new results are established for the problem. Using these results, a new algorithm is developed to find all the (d, T, b, P1, P2)-MPs, and its correctness is established. The algorithm is compared with a recently proposed one to show the practical efficiency of...

Evaluating Reliability of a Stochastic-flow Network in Terms of All Upper and Lower Boundary Points

, Ph.D. Dissertation Sharif University of Technology Forghani Elahabad, Majid (Author) ; Mahdavi Amiri, Nezam (Supervisor)

Abstract

In recent years, stochastic-flow networks (SFNs) have been extensively applied to many problems such as distribution, power transmission, and telecommunication. In quality management and decision making, an important task is to design some performance indices in order to measure the performance of an SFN. The system reliability and unreliability are such two common performance indices.Hitherto, several research works have been conducted for evaluating these two performance indices.One approach for evaluating the reliability of SFNs is determining all the upper or lower boundary points (respectively, UBPs or LBPs).Here, we study four problems to determine: (1) all the UBPs in a two-terminal...

A comparative study of different approaches for finding the upper boundary points in stochastic-flow networks

, Article International Journal of Enterprise Information Systems ; Volume 10, Issue 3 , 1 July , 2014 , Pages 13-20 ; ISSN: 15481115 Mansourzadeh, S. M ; Nasseri, S. H ; Forghani Elahabad, M ; Ebrahimnejad, A ; Sharif University of Technology

2014

Abstract

An information system network (ISN) can be modeled as a stochastic-flow network (SFN). There are several algorithms to evaluate reliability of an SFN in terms of Minimal Cuts (MCs). The existing algorithms commonly first find all the upper boundary points (called d-MCs) in an SFN, and then determine the reliability of the network using some approaches such as inclusion-exclusion method, sum of disjoint products, etc. However, most of the algorithms have been compared via complexity results or through one or two benchmark networks. Thus, comparing those algorithms through random test problems can be desired. Here, the authors first state a simple improved algorithm. Then, by generating a...

The Effect of Aging Phenomenon on Wear Behavior and Mechanical Properties of 7005 Series Aluminum Alloy

, M.Sc. Thesis Sharif University of Technology Forghani, Mohammad (Author) ; Serajzadeh, Siamak (Supervisor) ; Karimi Taheri, Ali (Supervisor)

Abstract

In this research, the effects of natural and artificial aging heat treatments on the mechanical and wear behavior of an aluminum alloy from the 7xxx series have been investigated. The study commenced with annealing of the received samples, which were subsequently divided into four categories. One of these categories was placed in a freezer as annealed samples, while the other two underwent artificial aging heat treatments at temperatures of 180 and 210 degrees Celsius. The final category naturally aged over time. As a result, different structures with varied distributions and morphologies of precipitates were formed, and the mechanical properties, mechanisms, and wear resistance of the...

Secrecy capacity scaling in large cooperative wireless networks

, Article IEEE Transactions on Information Theory ; Volume 63, Issue 3 , 2017 , Pages 1923-1939 ; 00189448 (ISSN) Mirmohseni, M ; Papadimitratos, P. P ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2017

Abstract

We investigate large wireless networks subject to security constraints. In contrast to point-to-point, interferencelimited communications considered in prior works, we propose active cooperative relaying-based schemes. We consider a network with nl legitimate nodes, ne eavesdroppers, and path loss exponent α ≥ 2. As long as n2e (log(ne))γ = o(nl ), for some positive γ , we show that one can obtain unbounded secure aggregate rate. This means zero-cost secure communication, given fixed total power constraint for the entire network. We achieve this result through: 1) the source using Wyner randomized encoder and a serial (multi-stage) block Markov scheme, to cooperate with the relays and 2) the...

Fast estimation of connectivity in fractured reservoirs using percolation theory

, Article SPE Journal ; Volume 12, Issue 2 , 2007 , Pages 167-178 ; 1086055X (ISSN) Masihi, M ; King, P. R ; Nuratza, P ; Sharif University of Technology

Society of Petroleum Engineers (SPE) 2007

Abstract

Investigating the impact of geological uncertainty (i.e., spatial distribution of fractures) on reservoir performance may aid management decisions. The conventional approach to address this is to build a number of possible reservoir models, upscale them, and then run flow simulations. The problem with this approach is that it is computationally very expensive. In this study, we use another approach based on the permeability contrasts that control the flow, called percolation approach. This assumes that the permeability disorder of a rock can be simplified to either permeable or impermeable. The advantage is that by using some universal laws from percolation theory, the effect of the complex...

A new decoding scheme for errorless codes for overloaded CDMA with active user detection

, Article 2011 18th International Conference on Telecommunications, ICT 2011, Ayia Napa, 8 May 2011 through 11 May 2011 ; 2011 , Pages 201-205 ; 9781457700248 (ISBN) Mousavi, A ; Pad, P ; Delgosha, P ; Marvasti, F ; Sharif University of Technology

2011

Abstract

Recently, a new class of binary codes for overloaded CDMA systems are proposed that not only has the ability of errorless communication but also suitable for detecting active users. These codes are called COWDA. In [1], a Maximum Likelihood (ML) decoder is proposed for this class of codes. Although the proposed scheme for coding/decoding shows impressive performance, the decoder can be significantly improved. In this paper, by assuming practical conditions for the traffic in the system, we suggest and prove an algorithm that increases the performance of the decoder several orders of magnitude (the Bit-Error-Rate (BER) is divided by a factor of about 400 in some E b/N0's). The algorithm...

Estimation of the Effective Permeability of Heterogeneous Porous Media by Using Percolation Concepts

, Article Transport in Porous Media ; Volume 114, Issue 1 , 2016 , Pages 169-199 ; 01693913 (ISSN) Masihi, M ; Gago, P. A ; King, P. R ; Sharif University of Technology

Springer Netherlands 2016

Abstract

In this paper we present new methods to estimate the effective permeability (keff) of heterogeneous porous media with a wide distribution of permeabilities and various underlying structures, using percolation concepts. We first set a threshold permeability (kth) on the permeability density function and use standard algorithms from percolation theory to check whether the high permeable grid blocks (i.e., those with permeability higher than kth) with occupied fraction of “p” first forms a cluster connecting two opposite sides of the system in the direction of the flow (high permeability flow pathway). Then we estimate the effective permeability of the heterogeneous porous media in different...

Percolation-based effective permeability estimation in real heterogeneous porous media

, Article 15th European Conference on the Mathematics of Oil Recovery, 29 August 2016 through 1 September 2016 ; 2016 ; 9462821933 (ISBN); 9789462821934 (ISBN) Masihi, M ; Gago, P ; King, P ; DCSE; Schlumberger; Shell ; Sharif University of Technology

European Association of Geoscientists and Engineers 2016

Abstract

It has long been understood that flow behavior in heterogeneous porous media is largely controlled by the continuity of permeability contrasts. With this in mind, we are looking in new methods for a fast estimation of the effective permeability which concentrates on the properties of the percolating cluster. From percolation concepts we use a threshold permeability value (Kth) by which the gridblocks with the highest permeability values connect two opposite side of the system in the direction of the flow. Those methods can be applied to heterogeneous media of a range of permeabilities distribution and various underlying structures. We use power law relations and weighted power averages that...