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Tiny graviton matrix theory/SYM correspondence: Analysis of BPS states
, Article Physical Review D - Particles, Fields, Gravitation and Cosmology ; Volume 74, Issue 6 , 2006 ; 15507998 (ISSN) ; Sheikh Jabbari, M. M ; Torabian, M ; Sharif University of Technology
2006
Abstract
In this paper we continue analysis of the Matrix theory describing the DLCQ of type IIB string theory on AdS5×S5 (and/or the plane-wave) background, i.e. the tiny graviton matrix theory (TGMT). We study and classify 1/2, 1/4, and 1/8 BPS solutions of the TGMT which are generically of the form of rotating three-brane giants. These are branes whose shape are deformed three-spheres and hyperboloids. In lack of a classification of such ten-dimensional type IIb supergravity configurations, we focus on the dual N=4 four-dimensional 1/2, 1/4, and one 1/8 BPS operators and show that they are in one-to-one correspondence with the states of the same set of quantum numbers in TGMT. This provides...
Extensions of AdS5 × S5 and the plane-wave superalgebras and their realization in the tiny graviton matrix theory
, Article Journal of High Energy Physics ; Issue 3 , 2006 , Pages 4613-4636 ; 10298479 (ISSN) ; Sheikh Jabbari, M. M ; Torabian, M ; Sharif University of Technology
2006
Abstract
In this paper we consider all consistent extensions of the AdS5 × S5 superalgebra, psu(2,2/4), to incorporate brane charges by introducing both bosonic and fermionic (non)central extensions. We study the Inönü-Wigner contraction of the extended psu(2,2/4) under the Penrose limit to obtain the most general consistent extension of the plane-wave superalgebra and compare these extensions with the possible BPS (flat or spherical) brane configurations in the plane-wave background. We give an explicit realization of some of these extensions in terms of the Tiny Graviton Matrix Theory (TGMT) [14] which is the 0+1 dimensional gauge theory conjectured to describe the DLCQ of strings on the AdS5 × S5...
Limited-sharing multi-party computation for massive matrix operations
, Article 2018 IEEE International Symposium on Information Theory, ISIT 2018, 17 June 2018 through 22 June 2018 ; Volume 2018-June , 2018 , Pages 1231-1235 ; 21578095 (ISSN) ; 9781538647806 (ISBN) ; Maddah Ali, M. A ; Sharif University of Technology
2018
Abstract
In this paper, we introduce limited-sharing multiparty 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 matrix for some cin{1, rac{1}{2},rac{1}{3}, ldots}. 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 tin mathbb{N}, collude, they...
Secure coded multi-party computation for massive matrix operations
, Article IEEE Transactions on Information Theory ; Volume 67, Issue 4 , 2021 , Pages 2379-2398 ; 00189448 (ISSN) ; Maddah Ali, M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In this article, we consider a secure multi-party computation problem (MPC), where the goal is to offload the computation of an arbitrary polynomial function of some massive private matrices (inputs) to a cluster of workers. The workers are not reliable. Some of them may collude to gain information about the input data (semi-honest workers). The system is initialized by sharing a (randomized) function of each input matrix to each server. Since the input matrices are massive, each share's size is assumed to be at most 1/k fraction of the input matrix, for some k ∈ N. The objective is to minimize the number of workers needed to perform the computation task correctly, such that even if an...
The relaxed three-algebras: their matrix representation and implications for multi M2-brane theory
, Article Journal of High Energy Physics ; Volume 2008, Issue 12 , 2008 ; 11266708 (ISSN) ; Sheikh Jabbari, M. M ; Simon, J ; Sharif University of Technology
2008
Abstract
We argue that one can relax the requirements of the non-associative three-algebras recently used in constructing D = 3, = 8 superconformal field theories, and introduce the notion of ''relaxed three-algebras''. We present a specific realization of the relaxed three-algebras in terms of classical Lie algebras with a matrix representation, endowed with a non-associative four-bracket structure which is prescribed to replace the three-brackets of the three-algebras. We show that both the so(4)-based solutions as well as the cases with non-positive definite metric find a uniform description in our setting. We discuss the implications of our four-bracket representation for the D = 3, = 8 and multi...
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...
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...
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...
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...
Total Domination Number in Graphs
, M.Sc. Thesis Sharif University of Technology ; Akbari, Saeed (Supervisor)
Abstract
In this dissertation we aim to survey the concepts and results concerning Total Domination Set. Consider graph G = (V;E). Let S be a subset of V . S is Total Domination Set in G if every vertex in V is adjacent to at least one vertex in S.Furthermore, we call S a k-Total Domination Set if every vertex in V is adjacent to at least k vertices in S. The size of the smallest Total Domination and k-Total Domination Set in a graph G is respectively called the Total Domination and k-Total Domination Number of G.Now, if there is a sequence of subsets of V like S = V0; V1; V2; : : : ; Vl = V so that for each i, every vertex in Vi is connected to at least k vertices in Vi1, S is a Dynamical k-Total...
An Investigation into the Effect of Prestrain Temperature on the Static
Recrystallization of low Carbon Steel
,
M.Sc. Thesis
Sharif University of Technology
;
karimi Taheri, Ali
(Supervisor)
Abstract
In this project the effect of rolling temperature on mechanical properties and microstructure evolution of a low carbon steel was studied. The steel was rolled up to a nominal strain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Micreohardnessand tensile tests were used to characterize the recrystallization kinetics. Optical and scanning electron microscopic examinations were carried out to evaluate the mechanical, grain size, and the kinetics of static recrystallization by the Avrami equation. The results indicated that the volume fraction of static recrystallization increases with the increase in annealing period. The Avrami exponent...
Secure coded multi-party computation for massive matrix operations
, Article IEEE Transactions on Information Theory ; Volume 67, Issue 4 , 2021 , Pages 2379-2398 ; 00189448 (ISSN) ; Maddah Ali, M.A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In this article, we consider a secure multi-party computation problem (MPC), where the goal is to offload the computation of an arbitrary polynomial function of some massive private matrices (inputs) to a cluster of workers. The workers are not reliable. Some of them may collude to gain information about the input data (semi-honest workers). The system is initialized by sharing a (randomized) function of each input matrix to each server. Since the input matrices are massive, each share's size is assumed to be at most 1/k fraction of the input matrix, for some k ∈ N. The objective is to minimize the number of workers needed to perform the computation task correctly, such that even if an...
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...
Instability Analysis of Carbon Nanotubes and Graphitic Shells Conveying Fluid
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
In this research, the instability analysis of single-walled carbon nanotubes (SWCNTs) and graphitic shells conveying fluid is investigated based on the molecular structural mechanics. Using the reduced order models for fluid and structure, the dynamic behavior of carbon nanotubes (CNTs) conveying fluid is accurately modeled via a few number of lowest flow modes and natural frequencies and mode shapes of CNTs structure. In addition, the boundary element method (BEM) is used to model the potential flow. The molecular mechanics (MM) model is applied to modal analysis and driving the natural frequencies and mode shapes of SWCNTs. The effect of chirality on flow-induced instability is taken into...
Laboratory Evaluation of Dynamic Viscosity and Heat Conductivity of Functionalized Carbon Nanotube Nano Fluids in the Engine Oil and Modeling with the Neural Network
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor) ; Akbari, Mohammad (Co-Advisor)
Abstract
In recent years, Rheological behavior and heat transfer of nanofluid studies have been increasing considerably and results show significant progress in this area. In this study we analyze the laboratory examination of the influence of parameters of volume fraction and temperature on thermal conductivity coefficient, dynamic viscosity of new and useful nanofluid carbon nanotube in engine oil. Most of fluid comparing to solid has lower thermal conductivity coefficient therefore solid particles increase thermal conductivity coefficient. On the other hand by adding particles, the dynamic viscosity of nanofluid also increases. Since nanoparticles have high volume ratio to surface (SSA) they have...
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...
Spur Level Reduction in Direct Digital Synthesizer
, M.Sc. Thesis Sharif University of Technology ; Akbari, Mahmoud (Supervisor) ; Banai, Ali ($item.subfieldsMap.e)
Abstract
Direct digital synthesizers (DDS) are one type of frequency synthesizer that are used for creating arbitrary waveforms from a reference clock with fixed-frequency and have various applications in signal generators, local oscillators in telecommunication systems, mixers, modulators and part of phase-locked loop.Despite of numerous advantages of direct digital synthesizers like high accuracy, fast switching ability, low power consumption and etc, beacuse of some available alternative errors in its structure like phase truncation, Inside band of desired output signal, independent unwanted signals namely spur were created. Spurs creat trouble in the use of sensor or radar systems and limit the...
Processor Allocation for Future Multi-Core Chip-Multiprocessor
, M.Sc. Thesis Sharif University of Technology ; Sarbazi Azad, Hamid (Supervisor)
Abstract
Since 2005, processor designers have increased core counts to exploit Moore’s Law scaling, rather than focusing on single-core performance. For decades, this approach provides desired performance for parallel and multithreaded workloads. On the other hand, rising of utilization wall limits the number of transistors that can be powered on in chip and result in a large region to be dark. So, same as before trend for performance scaling in future multi processor, an appropriate architecture is essential. There are some structures for this era which used specialization approach to cope with the limited power budget. Therefore, in this thesis, we propose a general-purpose platform that provides...