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    Modeling and optimization of friction materials based on genetic programming and experimental frictional data

    , Article Journal of Reinforced Plastics and Composites ; Volume 34, Issue 7 , 2015 , Pages 581-590 ; 07316844 (ISSN) Khazaei, A ; Shojaei, A ; Sharif University of Technology
    SAGE Publications Ltd  2015
    Abstract
    A genetic programming technique was employed to develop empirical models for predicting specific wear rate and coefficient of friction on brake friction materials. The models consist of independent variables representing the volume fraction of the ingredients. The average absolute relative error for specific wear rate and coefficient of friction were found to be 1.93% and 1.92%, respectively. The models were also verified by the experimental data used for further control of the formulation. Utilizing Tornado plots, the models were found to be able to properly demonstrate the role of the ingredients on overall tribological performance of the brake friction materials. Moreover, a non-dominated... 

    Adsorption dynamics of surface-modified silica nanoparticles at solid-liquid interfaces

    , Article Langmuir ; Volume 38, Issue 41 , 2022 , Pages 12421-12431 ; 07437463 (ISSN) Khazaei, M. A ; Bastani, D ; Mohammadi, A ; Kordzadeh, A ; Sharif University of Technology
    American Chemical Society  2022
    Abstract
    Understanding the adsorption dynamics of nanoparticles at solid-liquid interfaces is of paramount importance to engineer nanoparticles for a variety of applications. The nanoparticle surface chemistry is significant for controlling the adsorption dynamics. This study aimed to experimentally examine the adsorption of surface-modified round-shaped silica nanoparticles (with an average diameter of 12 nm), grafted with hydrophobic (propyl chains) and/or hydrophilic (polyethylene glycol chains) agents, at an aqueous solution-silica interface with spherical soda-lime glass beads (diameter of 3 mm) being used as adsorbents. While no measurable adsorption was observed for solely hydrophobic or... 

    Characterization of sol-gel derived silver/fluor-hydroxyapatite composite coatings on titanium substrate

    , Article Surface and Coatings Technology ; Volume 352 , 2018 , Pages 522-528 ; 02578972 (ISSN) Batebi, K ; Abbasi Khazaei, B ; Afshar, A ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    A composite coating containing silver, fluoride and hydroxyapatite (Ag-FHA) was developed on titanium substrate by sol-gel method. Triethylphosphite, hydrated calcium nitrate, ammonium fluoride and silver nitrate were used respectively, as P, Ca, F and Ag precursors with a Ca:P ratio 1.67 and concentration of silver was 0.3 wt%. Coatings were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and atomic absorption spectrometry (AAS). Potentiodynamic polarization measurements in simulated body fluid proved corrosion protection caused by both Ag-FHA coatings. Antibacterial activity of coatings against... 

    Relationship of profitability of world’s top companies with entrepreneurship, competitiveness, and business environment indicators

    , Article Applied Economics ; Volume 53, Issue 23 , December , 2020 , Pages 2584-2597 Khazaei, M ; Sharif University of Technology
    Routledge  2020
    Abstract
    Identifying the factors affecting profitability is important from the perspective of market players. One of the most important benchmarks of firm performance is accounting profit and effective factors analysis so that users of accounting information analyse the factors affecting profit, firm performance and various aspects of its performance and according to estimates Done, make your own decision on how to allocate resources. The main purpose of this study is to investigate the impact of some factors of competitiveness, entrepreneurship and business environment indicators on the profitability of the world’s top companies. For this purpose, 176 top companies in the world from 2013 to 2018... 

    Relationship of profitability of world’s top companies with entrepreneurship, competitiveness, and business environment indicators

    , Article Applied Economics ; Volume 53, Issue 23 , 2021 , Pages 2584-2597 ; 00036846 (ISSN) Khazaei, M ; Sharif University of Technology
    Routledge  2021
    Abstract
    Identifying the factors affecting profitability is important from the perspective of market players. One of the most important benchmarks of firm performance is accounting profit and effective factors analysis so that users of accounting information analyse the factors affecting profit, firm performance and various aspects of its performance and according to estimates Done, make your own decision on how to allocate resources. The main purpose of this study is to investigate the impact of some factors of competitiveness, entrepreneurship and business environment indicators on the profitability of the world’s top companies. For this purpose, 176 top companies in the world from 2013 to 2018... 

    Pervaporation of toluene and iso-octane through poly(vinyl alcohol)/graphene oxide nanoplate mixed matrix membranes: Comparison of crosslinked and noncrosslinked membranes

    , Article Journal of Applied Polymer Science ; Volume 135, Issue 7 , 2018 ; 00218995 (ISSN) Khazaei, A ; Mohebbi, V ; Behbahani, R. M ; Ramazani S. A., A ; Sharif University of Technology
    John Wiley and Sons Inc  2018
    Abstract
    Removal of aromatic compounds from fuel is an essential requirement in new environmental policies. In the present study, poly(vinyl alcohol)/graphene oxide (GO) mixed matrix membranes were prepared and applied to the separation of toluene from iso-octane by pervaporation, considering the similarity and interaction between graphene and aromatics. The effects of crosslinking and GO content on separation efficiency have been investigated in detail. Owing to the high affinity of GO with toluene through s and π bonds, the selectivity of the membranes was increased by incorporating a low amount of GO. The results also indicated that noncrosslinked membranes have higher selectivity and permeation... 

    Automated analysis of karyotype images

    , Article Journal of Bioinformatics and Computational Biology ; Volume 20, Issue 3 , 2022 ; 02197200 (ISSN) Khazaei, E ; Emrany, A ; Tavassolipour, M ; Mahjoubi, F ; Ebrahimi, A ; Motahari, S. A ; Sharif University of Technology
    World Scientific  2022
    Abstract
    Karyotype is a genetic test that is used for detection of chromosomal defects. In a karyotype test, an image is captured from chromosomes during the cell division. The captured images are then analyzed by cytogeneticists in order to detect possible chromosomal defects. In this paper, we have proposed an automated pipeline for analysis of karyotype images. There are three main steps for karyotype image analysis: image enhancement, image segmentation and chromosome classification. In this paper, we have proposed a novel chromosome segmentation algorithm to decompose overlapped chromosomes. We have also proposed a CNN-based classifier which outperforms all the existing classifiers. Our... 

    Dynamic localization of light in squeezed-like photonic lattices

    , Article Optics Communications ; Volume 367 , 2016 ; 00304018 (ISSN) Khazaei Nezhad, M ; Golshani, M ; Mahdavi, S. M ; Bahrampour, A. R ; Langari, A ; Sharif University of Technology
    Elsevier  2016
    Abstract
    We investigate the dynamic localization of light in the sinusoidal bent squeezed-like photonic lattices, a class of inhomogeneous semi-infinite waveguide arrays. Our findings show that, dynamic localization takes place for the normalized amplitude of sinusoidal profile (α) above a critical value α c. In this regime, for any normalized amplitude α>αc, there is a specific spatial period (ℓ) of waveguides, in which the dynamical oscillation, with the same spatial period occurs. Moreover, the specific spatial period is a decreasing function of the normalized amplitude α. Accordingly, the dynamical oscillation and self-imaging is realized, in spite of the existence of inhomogeneous coupling... 

    On The Behavior of Low-Rise, Irregular, Dual Structures

    , M.Sc. Thesis Sharif University of Technology Khazaei, Siamak (Author) ; Mofid, Masoud (Supervisor)
    Abstract
    The Response modification factor R represents the behavior of the structure such as ductility, overstrength and the inherent redundancy. This factor shall be defined according to the type of lateral force resisting system. However, there are some complexities and/or uncertainties in codes related to the R factor according to the height, form of irregularities and structural systems. Therefore, from the scientific point of view as well as reliability, it is very clear that the R factor cannot be similar for all kinds of structures, categorized as a specific group. In this investigation, assuming a low-rise, vertically irregular structure with a heliport which has a dual structural system... 

    Modeling and Optimization of Composite Brake Friction Materials Formulation

    , M.Sc. Thesis Sharif University of Technology Khazaei, Ali (Author) ; Shojaei, Akbar (Supervisor)
    Abstract
    Automotive brake pad is one of the most widely used composites. Commonly, more than 10 components are applied to make these materials and due to the large number of components and interactions between them, choice, explaination of the behavior and optimization of brake friction materials are some industry's challenges. Until now, some methods have been presented to design and optimization of these materials, but due to different complexities, there is lack of practical method that could be used for explaining the tribological behavior, engineering calculation and optimization of brake friction materials. Today, formulation of the current brake pads in the industry has mainly come from trial... 

    Reflection Cryptanalysis of GOST Block Cipher

    , M.Sc. Thesis Sharif University of Technology Oraei, Hossein (Author) ; khazaei, Shahram (Supervisor)
    Abstract
    Block ciphers are the central tool in the design of security protocols. GOST is a block cipher that several attacks have been published on it during the past 20 years. One of them is the reflection attack that was first introduced in 2007. This attack utilizes similarities of some round functions of both encryption and decryption processes. In addition, there are approaches that combines techniques of the reflection attack and variants of the meet-in-the-middle attack. In this thesis, we study reflection-based attacks on GOST. We first describe the GOST block cipher and the reflection attack. Then, we review previous reflectionbased attacks such as reflection-meet-in-the-middle attack and... 

    Linear-Differential Cryptanalysis of Word-Reduced Variants of Cubehash

    , M.Sc. Thesis Sharif University of Technology Javid, Sahand (Author) ; Khazaei, Shahram (Supervisor)
    Abstract
    In this thesis, first we will have a brief review on hash functions and related concepts.Then, we will descibe the hash function, Cubehash, which is one of the competitors in the competition held by NIST for selecting SHA-3 standard. Next, we will describe an attack based on linearization of differential paths in hash functions and apply this attack on Cubehash. At the end, we will discuss the results of this attack on Cubehash  

    Cryptographic Hash Functions from Expander Graphs

    , M.Sc. Thesis Sharif University of Technology Zarei, Afshin (Author) ; khazaei, Shahram (Supervisor)
    Abstract
    A hash function maps efficiently every finite length string to a fixed one. The output represents the entire content of the input, similar to digital fingerprint of input text. In order to be able to use a hash function in cryptography, it should be hard to find two distinct inputs with the same output (collision), because finding a collision in hash functions leads to malicious attacks on many security systems.We say a hash function is provably collision resistant, if finding a collision can be reduced to the known hard problems. Family of MD hash functions are one of the most famous applied hash functions which are considerably used in industrial applications. However, they are not... 

    Multiple human tracking using PHD filter in distributed camera network

    , Article Proceedings of the 4th International Conference on Computer and Knowledge Engineering, ICCKE 2014 ; 2014 , pp. 569-574 ; ISBN: 9781479954865 Khazaei, M ; Jamzad, M ; Sharif University of Technology
    2014
    Abstract
    The Gaussian mixture probability hypothesis density (GM-PHD) filter is a closed form approximation of the multi-target Bayes filter which can overcome most multitarget tracking problems. Limited field of view, decreasing cost of cameras, and advances of using multi-camera induce us to use large-scale camera networks. In this paper, a multihuman tracking framework using the PHD filter in a distributed camera network is proposed. Each camera tracks objects locally with PHD filter and a track-after-detect scheme and its estimates of targets are sent to neighboring nodes. Then each camera fuses its local estimates with it's neighbors. The proposed method is evaluated on the public PETS2009... 

    Randomized partial checking revisited

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) ; Volume 7779 LNCS , February , 2013 , Pages 115-128 ; 03029743 (ISSN) ; 9783642360947 (ISBN) Khazaei, S ; Wikstrom, D ; Sharif University of Technology
    2013
    Abstract
    We study mix-nets with randomized partial checking (RPC) as proposed by Jakobsson, Juels, and Rivest (2002). RPC is a technique to verify the correctness of an execution both for Chaumian and homomorphic mix-nets. The idea is to relax the correctness and privacy requirements to achieve a more efficient mix-net. We identify serious issues in the original description of mix-nets with RPC and show how to exploit these to break both correctness and privacy, both for Chaumian and homomorphic mix-nets. Our attacks are practical and applicable to real world mix-net implementations, e.g., the Civitas and the Scantegrity voting systems  

    Privacy Preserving Data Mining

    , M.Sc. Thesis Sharif University of Technology Javar, Zahra (Author) ; khazaei, Shahram (Supervisor)
    Abstract
    Increasing use of new data technologies have made data collection possible in large scales. Practicallity of the data relies upon the extraction of meaningful knowledge.Data mining is a solution to this problem. One of the new areas in data mining is consideration of the concern of privacy alongside the usefulness of the mining results.Main goal of privacy preserving data mining is to develop data mining models which only extract the useful knowledge. In recent years, many researches have been done in this area. Since the literature and notation of these published works vary, a survey would help to better understand these concepts. This thesis tries to explain, analyse,unify and categorize... 

    Return code schemes for electronic voting systems

    , Article 2nd International Joint Conference on Electronic Voting, E-Vote-ID 2017, 24 October 2017 through 27 October 2017 ; Volume 10615 LNCS , 2017 , Pages 198-209 ; 03029743 (ISSN); 9783319686868 (ISBN) Khazaei, S ; Wikström, D ; Sharif University of Technology
    Springer Verlag  2017
    Abstract
    We describe several return code schemes for secure vote submission in electronic voting systems. We consider a unified treatment where a return code is generated as a multiparty computation of a secure MAC tag applied on an encrypted message submitted by a voter. Our proposals enjoy a great level of flexibility with respect to various usability, security, and performance tradeoffs. © 2017, Springer International Publishing AG  

    A Study in Bound of Graph and Generalized Access Structures

    , M.Sc. Thesis Sharif University of Technology Nasirzadeh, Sajjad (Author) ; khazaei, Shahram (Supervisor)
    Abstract
    Determining the value of optimal information ratio for a given access structure and finding the upper and lower bounds for the information ratio in secreet sharing is one of the main problems that has been studied over time. In this thesis, we have tried to introduce the tools used in this field, including polymatroids and Shannon’s inequalities, linear programming, decomposition and etc, examine the papers presented in this field and rewrite obtained results in a simpler way  

    Determining Regions of Linear Contribution Vectors of Small Access Structures

    , M.Sc. Thesis Sharif University of Technology Bahariyan, Sorush (Author) ; Khazaei, Shahram (Supervisor)
    Abstract
    Objective of Secret Sharing is assigning some random variable which will be called shares, generated based on a random variable called secret, to some participant such that only specific subsets of participants could reconstruct the secret by polling their shares together. Constructing shares as small as possible is desired, hence notions like information ratio and average information ratio have been studied and considered to be a measure of efficiency of secret sharing schemes. In this research contribution vectors of access structures with five participants and graph based access structures with six participants have been studied. Small access structures have been considered shortly after... 

    Ciphertext-only attack on d × d Hill in O(d13d)

    , Article Information Processing Letters ; Volume 118 , 2017 , Pages 25-29 ; 00200190 (ISSN) Khazaei, S ; Ahmadi, S ; Sharif University of Technology
    Elsevier B.V  2017
    Abstract
    Hill is a classical cipher which is generally believed to be resistant against ciphertext-only attack. In this paper, by using a divide-and-conquer technique, it is first shown that Hill with d×d key matrix over Z26 can be broken with computational complexity of O(d26d), for the English language. This is much less than the only publicly known attack, i.e., the brute-force with complexity of O(d326d2). Then by using the Chinese Remainder Theorem, it is shown that the computational complexity of the proposed attack can be reduced down to O(d13d). Using an information-theoretic approach, it is shown that the minimum ciphertext length required for a successful attack increases by a factor of...