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#### Shell-like instability of large diameter single-walled carbon nanotubes conveying fluid

, Article Journal of Mechanical Science and Technology ; Volume 26, Issue 11 , 2012 , Pages 3389-3397 ; 1738494X (ISSN) ; Firouz Abadi, R. D ; Haddadpour, H ; Noorian, M. A ; Sharif University of Technology
2012

Abstract

The instability of large diameter single-walled carbon nanotubes (SWCNTs) conveying fluid is investigated based on the molecular mechanics. Using the modal expansion for structural displacements, the governing equations of coupled fluid-structural dynamics of SWCNTs are derived. The natural frequencies and mode shape of the SWCNTs are obtained based on the molecular structural mechanics to account for the effect of chirality and discrete nature of SWCNTs. The results show that the vibrational behavior of large diameter SWCNTs conveying fluid is size dependent, but the effect of chirality is negligible. The obtained results are compared with the equivalent continuum-based model in the...

#### Bridged single-walled carbon nanotube-based atomic-scale mass sensors

, Article Applied Physics A: Materials Science and Processing ; Volume 122, Issue 8 , Volume 122, Issue 8 , 2016 ; 09478396 (ISSN) ; Shaat, M ; Abdelkefi, A ; Sharif University of Technology
Springer Verlag
2016

Abstract

The potentials of carbon nanotubes (CNTs) as mechanical resonators for atomic-scale mass sensing are presented. To this aim, a nonlocal continuum-based model is proposed to study the dynamic behavior of bridged single-walled carbon nanotube-based mass nanosensors. The carbon nanotube (CNT) is considered as an elastic Euler–Bernoulli beam with von Kármán type geometric nonlinearity. Eringen’s nonlocal elastic field theory is utilized to model the interatomic long-range interactions within the structure of the CNT. This developed model accounts for the arbitrary position of the deposited atomic-mass. The natural frequencies and associated mode shapes are determined based on an eigenvalue...

#### Nonlinear performance analysis of forced carbon nanotube-based bio-mass sensors

, Article International Journal of Mechanics and Materials in Design ; 2018 ; 15691713 (ISSN) ; Ceballes, S ; Abdelkefi, A ; Sharif University of Technology
Springer Netherlands
2018

Abstract

In this effort, an analytical solution is proposed for the large amplitude nonlinear vibrations of doubly clamped carbon nanotube (CNT)-based nano-scale bio-mass sensors. The single walled CNT is modeled as an elastic Euler–Bernoulli nano-scale beam and the size effects are introduced into the mathematical model of the system through Eringen’s nonlocal elastic field theory. The nonlinearity arises due to mid-plane stretching of the bridged CNT, and is accounted for as the von Kármán nonlinearity. The impacts of deposited nano-scale bio-object, its geometrical properties, and its landing position along the longitudinal axis of the CNT-based resonator are considered. The nonlinear equations of...

#### Nonlinear performance analysis of forced carbon nanotube-based bio-mass sensors

, Article International Journal of Mechanics and Materials in Design ; Volume 15, Issue 2 , 2019 , Pages 291-315 ; 15691713 (ISSN) ; Ceballes, S ; Abdelkefi, A ; Sharif University of Technology
Springer Netherlands
2019

Abstract

In this effort, an analytical solution is proposed for the large amplitude nonlinear vibrations of doubly clamped carbon nanotube (CNT)-based nano-scale bio-mass sensors. The single walled CNT is modeled as an elastic Euler–Bernoulli nano-scale beam and the size effects are introduced into the mathematical model of the system through Eringen’s nonlocal elastic field theory. The nonlinearity arises due to mid-plane stretching of the bridged CNT, and is accounted for as the von Kármán nonlinearity. The impacts of deposited nano-scale bio-object, its geometrical properties, and its landing position along the longitudinal axis of the CNT-based resonator are considered. The nonlinear equations of...

#### Geometrical influence of a deposited particle on the performance of bridged carbon nanotube-based mass detectors

, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 94 , 2017 , Pages 31-46 ; 13869477 (ISSN) ; Ceballes, S ; Abdelkefi, A ; Sharif University of Technology
2017

Abstract

A nonlocal continuum-based model is derived to simulate the dynamic behavior of bridged carbon nanotube-based nano-scale mass detectors. The carbon nanotube (CNT) is modeled as an elastic Euler-Bernoulli beam considering von-Kármán type geometric nonlinearity. In order to achieve better accuracy in characterization of the CNTs, the geometrical properties of an attached nano-scale particle are introduced into the model by its moment of inertia with respect to the central axis of the beam. The inter-atomic long-range interactions within the structure of the CNT are incorporated into the model using Eringen's nonlocal elastic field theory. In this model, the mass can be deposited along an...

#### Some relations among term rank, clique number and list chromatic number of a graph

, Article Discrete Mathematics ; Volume 306, Issue 23 SPEC. ISS , 2006 , Pages 3078-3082 ; 0012365X (ISSN) ; Fanaï, H. R ; Sharif University of Technology
Elsevier
2006

Abstract

Let G be a graph with a nonempty edge set, we denote the rank of the adjacency matrix of G and term rank of G, by rk (G) and Rk (G), respectively. van Nuffelen conjectured that for any graph G, χ (G) ≤ rk (G). The first counterexample to this conjecture was obtained by Alon and Seymour. In 2002, Fishkind and Kotlov proved that for any graph G, χ (G) ≤ Rk (G). Here we improve this upper bound and show that χl (G) ≤ (rk (G) + Rk (G)) / 2, where χl (G) is the list chromatic number of G. © 2006 Elsevier B.V. All rights reserved

#### Rank, term rank and chromatic number of a graph

, Article Comptes Rendus Mathematique ; Volume 340, Issue 3 , 2005 , Pages 181-184 ; 1631073X (ISSN) ; Fanaï, H. R ; Sharif University of Technology
2005

Abstract

Let G be a graph with a nonempty edge set, we denote the rank of the adjacency matrix of G and the term rank of G, by rk (G) and Rk (G), respectively. It was conjectured [C. van Nuffelen, Amer. Math. Monthly 83 (1976) 265-266], for any graph G, χ (G) ≤ rk (G). The first counterexample to this conjecture was obtained by Alon and Seymour [J. Graph Theor. 13 (1989) 523-525]. Recently, Fishkind and Kotlov [Discrete Math. 250 (2002) 253-257] have proved that for any graph G, χ (G) ≤ Rk (G). In this Note we improve Fishkind-Kotlov upper bound and show that χ (G) ≤ rk(G)+Rk(G)/2. © 2004 Académie des sciences. Published by Elsevier SAS. All rights reserved

#### From-Focused Second Language Vocabulary Learning: A Case for Translation and Dictionary Search

, M.Sc. Thesis Sharif University of Technology ; Jahangard, Ali (Supervisor)
Abstract

The purpose of the study was four-fold: first to investigate the predictive adequacy of the Task-Induced Involvement Load Hypothesis which contends that higher-load inducing tasks yield better retention rates in incidental learning situations, second, to examine whether type of dictionary search could affect vocabulary retention, third, to investigate the effect of translation direction on retention rate, and finally to determine the most effective tasks. To meet these ends, six groups of EFL learners - all male, aging 19-25, majoring in various fields of engineering sciences were assigned to the study. Each one of the groups performed distinct tasks which were as follow: reading...

#### Entangled polynomial coding in limited-sharing multi-party computation

, Article 2018 IEEE Information Theory Workshop, ITW 2018, 25 November 2018 through 29 November 2018 ; 2019 ; 9781538635995 (ISBN) ; Hoseini Najarkolaei, S. R ; Maddah Ali, M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019

Abstract

In a secure multiparty computation (MPC) system, there are some sources, where each one has access to a private input. The sources want to offload the computation of a polynomial function of the inputs to some processing nodes or workers. The processors are unreliable, i.e., a limited number of them may collude to gain information about the inputs. The objective is to minimize the number of required workers to calculate the polynomial, while the colluding workers gain no information about inputs. In this paper, we assume that the inputs are massive matrices, while the workers have the limited computation and storage at each worker. As proxy for that, we assume the link between each source...

#### Performance analysis of packet loss recovery policies in P2P video streaming

, Article International Journal of Internet Protocol Technology ; Vol. 8, issue. 1 , 2014 , p. 44-53 ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
2014

Abstract

Packet loss recovery is an important part of P2P video streaming networks due to inevitable packet loss in today's internet and interdependency of data units in compressed video streams. In addition, the architecture of P2P streaming networks, in which the data delivered to the receivers through chain of peers, can intensify the impact of the internet packet loss on the quality of perceived video at the receivers. FEC and ARQ are the two most important techniques that can be used to overcome the side effect of the internet packet loss in P2P video streaming networks. Based on these two techniques, different packet loss recovery strategies can be applied in different overlay hops of a given...

#### Packet loss in peer-to-peer video streaming over the Internet

, Article Multimedia Systems ; Volume 13, Issue 5-6 , 2008 , Pages 345-361 ; 09424962 (ISSN) ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
2008

Abstract

Peer-to-peer streaming has recently gained attention as an effective solution to support large scale media streaming applications over the Internet. One of the main challenges of peer-to-peer video streaming is the cumulative impact of the Internet packet loss due to the decoding dependency of the compressed video frames. In this paper we study the impact of the Internet packet loss on the performance of peer-to-peer video streaming systems, and analyze the efficiency of various packet loss recovery policies in such systems. Our analytical and simulation results show how the Internet packet loss can affect the performance of peer- to-peer video streaming systems and how different packet loss...

#### A rate-efficient peer-to-peer architecture for video multicasting over the Internet

, Article Seventh IEEE International Symposium on Multimedia, ISM 2005, Irvine, CA, 12 December 2005 through 14 December 2005 ; Volume 2005 , 2005 , Pages 438-446 ; 0769524893 (ISBN); 9780769524894 (ISBN) ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
2005

Abstract

In this paper we propose a rate-efficient peer-to-peer architecture for video multicasting over the Internet. The limited capacity of the Internet hosts and the heterogeneous property of their access links are the main challenges of the peer-to-peer video multicasting over the Internet. Although, the rate-optimized overlay tree construction is a NP-hard problem, we propose a number of distributed and efficient protocols for rate-efficient overlay tree construction. Our proposed protocols include efficient join, improvement, overlay tree refinement and an optimum rate allocation protocol. The simulation results show the efficiency of the proposed protocols in rate-efficient overlay tree...

#### Minimal defining sets for full 2-(v, 3, v - 2) designs

, Article Australasian Journal of Combinatorics ; Volume 23 , 2001 , Pages 5-8 ; 10344942 (ISSN) ; Maimani, H. R ; Maysoori, C ; Sharif University of Technology
2001

Abstract

A t-(v, k, λ) design D = (X, B) with B = Pk(X) is called a full design. For t = 2, k; = 3 and any v, we give minimal defining sets for these designs. For v = 6 and v = 7, smallest defining sets are found

#### DPOCS: A dynamic proxy architecture for video streaming based on overlay network

, Article 2005 13th IEEE International Conference on Networks jointly held with the 2005 7th IEEE Malaysia International Conference on Communications, Kuala Lumpur, 16 November 2005 through 18 November 2005 ; Volume 1 , 2005 , Pages 384-389 ; 1424400007 (ISBN); 9781424400003 (ISBN) ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
2005

Abstract

In this paper, a new dynamic proxy solution based on overlay multicasting network for layered video streaming is presented. In our proposed approach, all clients in an Internet service provider network interested in receiving a video stream, provided by a media server in the Internet, organize themselves into an overlay tree. The root of the overlay tree acts as a proxy and receives video stream from original server and distributes it in the local overlay tree. In addition to introducing a new architecture, our main contribution in this paper is proposing a number of distributed protocols for construction and improvement of local overlay tree in video streaming applications. The experimental...

#### When a zero-divisor graph is planar or a complete r-partite graph

, Article Journal of Algebra ; Volume 270, Issue 1 , 2003 , Pages 169-180 ; 00218693 (ISSN) ; Maimani, H. R ; Yassemi, S ; Sharif University of Technology
Academic Press Inc
2003

Abstract

Let Γ(R) be the zero-divisor graph of a commutative ring R. An interesting question was proposed by Anderson, Frazier, Lauve, and Livingston: For which finite commutative rings R is Γ (R) planar? We give an answer to this question. More precisely, we prove that if R is a local ring with at least 33 elements, and Γ(R) ≠ 0, then Γ(R) is not planar. We use the set of the associated primes to find the minimal length of a cycle in Γ(R). Also, we determine the rings whose zero-divisor graphs are complete r-partite graphs and show that for any ring R and prime number p, p ≥ 3, if Γ(R) is a finite complete p-partite graph, then Z(R) = p2, R = p3, and R is isomorphic to exactly one of the rings ℤp3,...

#### On the matrices with constant determinant and permanent over roots of unity

, Article Linear Algebra and Its Applications ; Volume 375, Issue 1-3 , 2003 , Pages 245-249 ; 00243795 (ISSN) ; Fanaï, H. R ; Mahmoudian, K ; Sharif University of Technology
2003

Abstract

Let μm be the group of mth roots of unity. In this paper it is shown that if m is a prime power, then the number of all square matrices (of any order) over μm with non-zero constant determinant or permanent is finite. If m is not a prime power, we construct an infinite family of matrices over μm with determinant one. Also we prove that there is no n×n matrix over μp with vanishing permanent, where p is a prime and n = pα-1. © 2003 Elsevier Inc. All rights reserved

#### Application of Coding in Multi-party Computation for Massive Operations

, M.Sc. Thesis Sharif University of Technology ; Maddah-Ali, Mohammad Ali (Supervisor)
Abstract

In this thesis, we introduce limited-sharing multi-party computation; in which there is a network of workers (processors) and a set of sources, each having access to a massive matrix as a private input. These sources aim to offload the task of computing a polynomial function of the matrices to the workers, while preserving the privacy of data. We also assume that the load of the link between each source and each worker is upper bounded by a fraction of each input. The objective is to minimize the number of workers needed to perform the computation, such that even if an arbitrary subset of t 1 workers, for some t 2 N, collude, they cannot gain any information about the input matrices. This...

#### Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked kappa C-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties [electronic resource]

, Article Journal of Applied Polymer Science ; Vol.98, No.1, 255-263, 2005 ; Hosseinzadeh, H ; Mazidi, R
Abstract

To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (KC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N',N'-tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N'-methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for KC-g-AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature,...

#### Kavosh: An intelligent neuro-fuzzy search engine

, Article 7th International Conference on Intelligent Systems Design and Applications, ISDA'07, Rio de Janeiro, 22 October 2007 through 24 October 2007 ; November , 2007 , Pages 597-602 ; 0769529763 (ISBN); 9780769529769 (ISBN) ; Ghaemi, R ; Akbarzadeh-T., M. R ; Akbari, H ; Sharif University of Technology
2007

Abstract

In this paper we propose a neuro-fuzzy architecture for Web content taxonomy using hybrid of Adaptive Resonance Theory (ART) neural networks and fuzzy logic concept. The search engine called Kavosh1 is equipped with unsupervised neural networks for dynamic data clustering. This model was designed for retrieving images without metadata and in estimating resemblance of multimedia documents; however, in this work only text mining method is implemented. Results show noticeable average precision and recall over search results. © 2007 IEEE

#### Signed graphs cospectral with the path

, Article Linear Algebra and Its Applications ; Volume 553 , 2018 , Pages 104-116 ; 00243795 (ISSN) ; Haemers, W. H ; Maimani, H. R ; Parsaei Majd, L ; Sharif University of Technology
Elsevier Inc
2018

Abstract

A signed graph Γ is said to be determined by its spectrum if every signed graph with the same spectrum as Γ is switching isomorphic with Γ. Here it is proved that the path Pn, interpreted as a signed graph, is determined by its spectrum if and only if n≡0,1, or 2 (mod 4), unless n∈{8,13,14,17,29}, or n=3. © 2018 Elsevier Inc