Mixed mode fracture analysis of adiabatic cracks in homogeneous and non-homogeneous materials in the framework of partition of unity and the path-independent interaction integral

, Article Engineering Fracture Mechanics ; Vol. 131, issue , 2014 , Pp. 100-127 ; ISSN: 00137944 Goli, E ; Bayesteh, H ; Mohammadi, S ; Sharif University of Technology

2014

Abstract

In this paper, the path independent interaction integral has been implemented in the framework of the extended finite element method for mixed mode adiabatic cracks under thermo-mechanical loadings particularly in orthotropic non-homogenous materials. The mesh insensitivity and increased accuracy due to the thermal and displacement asymptotic analytical solutions are discussed and the contour independency of the interaction integral is investigated in different examples. Finally, the problem of crack propagation in orthotropic FGM materials under the thermal loading is investigated to assess the accuracy and robustness of proposed approach

Trade Liberalization and Wage Inequality in Iran’s Industries

, M.Sc. Thesis Sharif University of Technology Goli, Younes (Author) ; Keshavarz Haddad, GholamReza (Supervisor)

Abstract

This study examins effects of trade liberalization on the wage inequality across industries and between genders within these industries by utilizing the data of micro-level Households’ Income and Expenditures surveys and trade statistics over 2001-2011. The analysis is carried based on the Heckscher–Ohlin’s theory in international trade and Baker’s taste discrimination theory at firms. We use Quantile regression and ordinary least squares (OLS) to consider the wage discrimination across entire distribution wage distribution and at wages mean as well. The results of Blinder-Oaxaca decomposition approach (inequality at mean wage) and Machado and Mata’s model (inequality of wage at entire...

Numerical Modeling of Fracture Mechanics in Isotropic/ Orthotropic FGMs by XFEM

, M.Sc. Thesis Sharif University of Technology Goli, Elyas (Author) ; Kazemi, Mohammad Taghi (Supervisor)

Abstract

Nowadays, regarding to knowledge progresses in various fields,advanced materials for which have acceptable performance in sensitive and special conditions must be used. Functionally graded materials are advanced multiphase composite materials that are characterized by continues spatial variations in mechanical and thermal properties. Clearly, studying on fracture mechanics of FGMs is important because they are used in igh-tech and sensitive applications.In this research, numerical modeling of fracture mechanics in isotropic/orthotropic/ transversely isotropic FGMs via interaction integral method is performed. Both incompatible and non-equilibrium formulations of interaction integral are...

Community Detection in Very Large Networks

, M.Sc. Thesis Sharif University of Technology Goli, Amir Hossein (Author) ; Beigy, Hamid (Supervisor)

Abstract

Nowadays Systems in different fields of research like computer science, biology, social networks, information networks, and economics are modeled as graphs. The graphs which model real world systems have very different topological characteristics than those of classic networks. One of the prominent characteristics of these networks, is that its not practical to describe a general model for their structure and behavior. As a consequence of this complexity in modeling and structure, these networks are called complex networks. One of the most important observations in complex networks is the presence of communities, it means that in such networks one can separate vertices in disjoint sets, such...

Universal bounds on the scaling behavior of polar codes

, Article IEEE International Symposium on Information Theory - Proceedings ; 2012 , Pages 1957-1961 ; 9781467325790 (ISBN) Goli, A ; Hassani, S. H ; Urbanke, R ; Sharif University of Technology

IEEE 2012

Abstract

We consider the problem of determining the tradeoff between the rate and the block-length of polar codes for a given block error probability when we use the successive cancellation decoder. We take the sum of the Bhattacharyya parameters as a proxy for the block error probability, and show that there exists a universal parameter μ such that for any binary memoryless symmetric channel W with capacity I(W), reliable communication requires rates that satisfy R < I(W) - αN -1/μ, where α is a positive constant and N is the block-length. We provide lower bounds on μ, namely μ ≥ 3.553, and we conjecture that indeed μ = 3.627, the parameter for the binary erasure channel

An efficient distributed cluster-head election technique for load balancing in wireless sensor network

, Article Proceedings of the 2010 6th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, ISSNIP 2010, 7 December 2010 through 10 December 2010, Brisbane, QLD ; 2010 , Pages 227-232 ; 9781424471768 (ISBN) Afkhami Goli, S ; Yousefi, H ; Movaghar, A ; Sharif University of Technology

2010

Abstract

Energy constraint is the most critical problem in wireless sensor networks (WSNs). To address this issue, clustering has been introduced as an efficient way for routing. However, the available clustering algorithms do not efficiently consider the geographical information of nodes in cluster-head election. This leads to uneven distribution of cluster-heads and unbalanced cluster sizes that brings about uneven energy dissipation in clusters. In this paper, an Efficient Distributed Cluster-head Election technique for Load balancing (EDCEL) is proposed. The main criterion of the algorithm, dispersal of cluster-heads, is achieved by increasing the Euclidian distance between cluster-heads....

Simplified MAP-MUD for active user CDMA

, Article IEEE Communications Letters ; Volume 15, Issue 6 , April , 2011 , Pages 599-601 ; 10897798 (ISSN) Pad, P ; Mousavi, A ; Goli, A ; Marvasti, F ; Sharif University of Technology

2011

Abstract

In CDMA systems with variable number of users, the decoder consists of two stages. The first stage is the active user identification and the second one is the multi-user detection. Most of the proposed active user identification methods fail to work in overloaded CDMA systems (when the number of users is more than the spreading factor). In this paper we propose a joint active user identification and multi-user detection for binary input CDMA systems using the Viterbi algorithm. We will show that the proposed identification/detection method is Maximum A posteriori Probability (MAP) and outperforms the pervious results. In addition, some suboptimum decoders will be proposed that have lower...

A Cluster-Head Election Technique for Data Aggregation in Wireless Sensor Networks

, M.Sc. Thesis Sharif University of Technology Afkhami Goli, Sepideh (Author) ; Movaghar, Ali (Supervisor) ; Manzouri, Mohammad Taghi (Supervisor)

Abstract

Energy constraint is the most critical problem in wireless sensor networks (WSNs). To address this issue, clustering has been introduced as an efficient way for data aggregation and routing. However, there also exist some disadvantages associated with the clustering scheme, such as additional overheads during the cluster-head election and cluster formation process. Most available clustering algorithms do not efficiently take into consideration the geographical information of nodes in the cluster-head election. This leads to uneven distribution of cluster-heads and unbalanced cluster sizes, which brings about uneven energy dissipation in clusters. In this research, an Efficient Distributed...

Dose-dependent effects of nanoscale graphene oxide on reproduction capability of mammals

, Article Carbon ; Volume 95 , December , 2015 , Pages 309-317 ; 00086223 (ISSN) Akhavan, O ; Ghaderi, E ; Hashemi, E ; Akbari, E ; Sharif University of Technology

Elsevier Ltd 2015

Abstract

In vivo dose-dependent effects of nanoscale graphene oxide (NGO) sheets on reproduction capability of Balb/C mice were investigated. Biodistribution study of the NGO sheets (intravenously injected into male mice at dose of ∼2000 μg/mL or 4 mg/kg of body weight) showed a high graphene uptake in testis. Hence, in vivo effects of the NGO sheets on important characteristics of spermatozoa (including their viability, morphology, kinetics, DNA damage and chromosomal aberration) were evaluated. Significant in vivo effects was found at the injected concentrations ≥200 μg/mL after (e.g., ∼45% reduction in sperm viability and motility at 2000 μg/mL). Observation of remarkable DNA fragmentations and...

Accelerated differentiation of neural stem cells into neurons on ginseng-reduced graphene oxide sheets

, Article Carbon ; Volume 66 , January , 2014 , Pages 395-406 Akhavan, O ; Ghaderi, E ; Abouei, E ; Hatamie, S ; Ghasemi, E ; Sharif University of Technology

2014

Abstract

Asian red ginseng was used for green reduction of chemically exfoliated graphene oxide (GO) into reduced graphene oxide (rGO). The reduction level and electrical conductivity of the ginseng-rGO sheets were comparable to those of hydrazine-rGO ones. Reduction by ginseng resulted in repairing the sp 2 graphitic structure of the rGO, while hydrazine-rGO showed more defects and/or smaller aromatic domains. The ginseng-rGO sheets presented a better stability against aggregation than the hydrazine-rGO ones in an aqueous suspension. Whilst the hydrophobic hydrazine-rGO films exhibited no toxicity against human neural stem cells (hNSCs), the hydrophilic GO and ginseng-rGO films (as more...

Contested framings and policy controversies: Analysing biosafety policy-making in Iran

, Article Science and Public Policy ; Volume 40, Issue 5 , 2013 , Pages 616-627 ; 03023427 (ISSN) Kashani, E. S ; Millstone, E ; Sharif University of Technology

2013

Abstract

Vigorous debates have taken place within and between many countries about regulatory policy regimes covering the assessment and approval of genetically modified (GM) crops. In Iran, a very vigorous and hotly contested policy debate concerning legislation covering GM crops occurred between 2004 and 2009, but it was confined within government circles with almost no public discussion. This paper analyses the Iranian policy-making process in the period 2006-9. It explains how and why a stalemate arose in disputes between ministries and departments. The chosen analytical framework draws mainly on the regulation of technological risks and the analysis of public policy-making. It deploys the...

On the possible volumes of μ-way latin trades

, Article Aequationes Mathematicae ; Volume 63, Issue 3 , 2002 , Pages 303-320 ; 00019054 (ISSN) Adams, P ; Billington, E. J ; Bryant, D. E ; Mahmoodian, E. S ; Sharif University of Technology

Birkhauser Verlag Basel 2002

Abstract

A μ-way latin trade of volume s is a set of μ partial latin rectangles (of inconsequential size) containing exactly the same s filled cells, such that if cell (i, j) is filled, it contains a different entry in each of the μ partial latin rectangles, and such that row i in each of the μ partial latin rectangles contains, set-wise, the same symbols and column j, likewise. In this paper we show that all μ-way latin trades with sufficiently large volumes exist, and state some theorems on the non-existence of μ-way latin trades of certain volumes. We also find the set of possible volumes (that is, the volume spectrum) of μ-way latin trades for μ = 4 and 5. (The case μ = 2 was dealt with by Fu,...

The three-way intersection problem for latin squares

, Article Discrete Mathematics ; Volume 243, Issue 1-3 , 2002 , Pages 1-19 ; 0012365X (ISSN) Adams, P ; Billington, E. J ; Bryant, D. E ; Mahmoodian, E. S ; Sharif University of Technology

2002

Abstract

The set of integers k for which there exist three latin squares of order n having precisely k cells identical, with their remaining n2 -k cells different in all three latin squares, denoted by I3[n], is determined here for all orders n. In particular, it is shown that I3[n] = {0,.,n2 -15}U [n2 - 12,n2-9,n2], for n ≫8. ©2002 Eisevier Science B.V. All rights reserved

Integration of spatial fuzzy clustering with level set for segmentation of 2-D angiogram

, Article IECBES 2014, Conference Proceedings - 2014 IEEE Conference on Biomedical Engineering and Sciences: "Miri, Where Engineering in Medicine and Biology and Humanity Meet", 8 December 2014 through 10 December 2014 ; December , 2015 , Pages 309-314 ; 9781479940844 (ISBN) Ghalehnovi, M ; Zahedi, E ; Fatemizadeh, E ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2015

Abstract

Coronary angiography is a vital instrument to detect the prevailing of vascular diseases, and accurate vascular segmentation acts a crucial role for proper quantitative analysis of the vascular tree morphological features. Level set methods are popular for segmenting the coronary arteries, but their performance is related to suitable start-up and optimum setting of regulating parameters, essentially done manually. This research presents a novel fuzzy level set procedure with the objective of segmentation of the coronary artery tree in 2-D X-ray angiography as automatically. It is clever to clearly develop from the early segmentation with spatial fuzzy grouping. The adjusting parameters of...

Deep relative attributes

, Article 13th Asian Conference on Computer Vision, ACCV 2016, 20 November 2016 through 24 November 2016 ; Volume 10115 LNCS , 2017 , Pages 118-133 ; 03029743 (ISSN); 9783319541921 (ISBN) Souri, Y ; Noury, E ; Adeli, E ; Sharif University of Technology

Springer Verlag 2017

Abstract

Visual attributes are great means of describing images or scenes, in a way both humans and computers understand. In order to establish a correspondence between images and to be able to compare the strength of each property between images, relative attributes were introduced. However, since their introduction, hand-crafted and engineered features were used to learn increasingly complex models for the problem of relative attributes. This limits the applicability of those methods for more realistic cases. We introduce a deep neural network architecture for the task of relative attribute prediction. A convolutional neural network (ConvNet) is adopted to learn the features by including an...

A public code for astrometric microlensing with contour integration

, Article Monthly Notices of the Royal Astronomical Society ; Volume 505, Issue 1 , 2021 , Pages 126-135 ; 00358711 (ISSN) Bozza, V ; Khalouei, E ; Bachelet, E ; Sharif University of Technology

Oxford University Press 2021

Abstract

We present the first public code for the calculation of the astrometric centroid shift occurring during microlensing events. The computation is based on the contour integration scheme and covers single and binary lensing of finite sources with arbitrary limb darkening profiles. This allows for general detailed investigations of the impact of finite source size in astrometric binary microlensing. The new code is embedded in version 3.0 of vbbinarylensing, which offers a powerful computational tool for extensive studies of microlensing data from current surveys and future space missions. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society

Toward electrically tunable, lithography-free, ultra-thin color filters covering the whole visible spectrum

, Article Scientific Reports ; Volume 8, Issue 1 , 2018 ; 20452322 (ISSN) Aalizadeh, M ; Serebryannikov, A. E ; Khavasi, A ; Vandenbosch, G. A. E ; Ozbay, E ; Sharif University of Technology

Nature Publishing Group 2018

Abstract

The possibility of real-time tuning of optical devices has attracted a lot of interest over the last decade. At the same time, coming up with simple lithography-free structures has always been a challenge in the design of large-area compatible devices. In this work, we present the concept and the sample design of an electrically tunable, lithography-free, ultra-thin transmission-mode color filter, the spectrum of which continuously covers the whole visible region. A simple Metal-Insulator-Metal (MIM) cavity configuration is used. It is shown that using the electro-optic dielectric material of 4-dimethyl-amino-N-methyl-4-stilbazoliumtosylate (DAST) as the dielectric layer in this...

A novel method for modeling the magnetizing yoke

, Article Electromagnetics ; Volume 30, Issue 3 , 2010 , Pages 297-308 ; 02726343 (ISSN) Ravanbod, H ; Norouzi, E

2010

Abstract

Magnetic flux leakage is the most widely used method for oil and gas pipeline non destructive testing. The saturation level of the sample under test has a significant effect on its efficiency; therefore, the magnetizing yoke requires an elaborate design. The finite element method is the conventional approach used for this purpose, but it is very time consuming. In this article, a neuro-fuzzy method is presented to model the behavior of the magnetizing yoke. Modeling a few different designs with the finite element method and using the results for training the neuro-fuzzy model eradicates the necessity of modeling a huge number of designs with the finite element method. The acquired...

On decomposing complete tripartite graphs into 5-cycles

, Article Australasian Journal of Combinatorics ; Volume 54, Issue 2 , 2012 , Pages 289-301 ; 10344942 (ISSN) Alipour, S ; Mahmoodian, E. S ; Mollaahmadi, E ; Sharif University of Technology

AJC 2012

Abstract

The problem of finding necessary and sufficient conditions to decompose a complete tripartite graph K(r, s, t) into 5-cycles was first considered by Mahmoodian and Mirzakhani (1995). They stated some necessary conditions and conjectured that these conditions are also sufficient. Since then, many cases of the problem have been solved by various authors; however the case when the partite sets r ≤ s ≤ t have odd and distinct sizes remains open. A necessary condition is t ≤ 3r. Billington and Cavenagh (2011) have shown that when r, s, and t are all odd and r ≤ s ≤ t ≤ κr, where κ ≈ 1.0806, then the conjectured necessary conditions for decomposing are also sufficient. We extend this result...

Ultra-sensitive detection of leukemia by graphene

, Article Nanoscale ; Vol. 6, issue. 24 , Dec , 2014 , p. 14810-14819 Akhavan, O ; Ghaderi, E ; Hashemi, E ; Rahighi, R ; Sharif Universit of Technology

2014

Abstract

Graphene oxide nanoplatelets (GONPs) with extremely sharp edges (lateral dimensions ∼20-200 nm and thicknesses <2 nm) were applied in extraction of the overexpressed guanine synthesized in the cytoplasm of leukemia cells. The blood serums containing the extracted guanine were used in differential pulse voltammetry (DPV) with reduced graphene oxide nanowall (rGONW) electrodes to develop fast and ultra-sensitive electrochemical detection of leukemia cells at leukemia fractions (LFs) of ∼10-11 (as the lower detection limit). The stability of the DPV signals obtained by oxidation of the extracted guanine on the rGONWs was studied after 20 cycles. Without the guanine extraction, the DPV peaks...