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On zero-error molecular communication with multiple molecule types
, Article IEEE Transactions on Communications ; Volume 68, Issue 7 , 2020 , Pages 4311-4324 ; Gohari, A ; Mirmohseni, M ; Nasiri Kenari, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
In this paper, we study the zero error capacity of the molecular delay channel when multiple molecule types are available at the transmitter. In the molecular delay channel, each transmitted molecule (of any type) is received by a delay of at most k time slots. Depending on the number of molecules that the transmitter is allowed to release in each time slot, we consider the following three cases: (i) when the maximum number of the released molecules of each type in each time slot is restricted (ii) when the total number of the released molecules (regardless of their type) in each time slot is restricted, and (iii) when the transmitter can use only one molecule type (of its choice) in each...
Distributed Encoding System in the Presence of Adversarial Sources
, Ph.D. Dissertation Sharif University of Technology ; Maddah Ali, Mohammad Ali (Supervisor)
Abstract
In communications systems, coding is used to combat channel errors. The redundancy introduced by coding enables the detection and/or correction of errors occurring in the channel. In addition to communications systems, coding is also beneficial in various other systems such as distributed storage systems and blockchain systems to cope with node failures, data erasures, and adversarial behaviors attempting to modify information. In existing applications of coding, it is generally assumed that the encoding operation is performed correctly and without errors, and errors are applied to the encoded data. In recent years, applications have emerged where the assumption of error-free encoding is not...
Fundamental limits of distributed linear encoding
, Article IEEE Transactions on Information Theory ; Volume 67, Issue 12 , 2021 , Pages 7985-7998 ; 00189448 (ISSN) ; Maddah Ali, M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In general coding theory, we often assume that error is observed in transferring or storing encoded symbols, while the process of encoding itself is error-free. Motivated by recent applications of coding theory, in this paper, we consider the case where the process of encoding is distributed and prone to error. We introduce the problem of distributed encoding, comprised of a set of K ∈ N isolated source nodes and N ∈ N encoding nodes. Each source node has one symbol from a finite field, which is sent to each of the encoding nodes. Each encoding node stores an encoded symbol from the same field, as a function of the received symbols. However, some of the source nodes are controlled by the...
Fundamental limits of distributed encoding
, Article 2020 IEEE International Symposium on Information Theory, ISIT 2020, 21 July 2020 through 26 July 2020 ; Volume 2020-June , August , 2020 , Pages 798-803 ; Maddah Ali, M. A ; IEEE Information Theory Society; The Institute of Electrical and Electronics Engineers ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
In general coding theory, we often assume that error is observed in transferring or storing encoded symbols, while the process of encoding itself is error-free. Motivated by recent applications of coding theory, we introduce the problem of distributed encoding which is comprised of a set of K ϵ isolated source nodes and N ϵ encoding nodes. Each source node has one symbol from a finite field, which is sent to each of the encoding nodes. Each encoding node stores an encoded symbol from the same field, as a function of the received symbols. However, some of the source nodes are controlled by the adversary and may send different symbols to different encoding nodes. Depending on the number of...
The discrepancy attack on polyshard-ed blockchains
, Article 2021 IEEE International Symposium on Information Theory, ISIT 2021, 12 July 2021 through 20 July 2021 ; Volume 2021-July , 2021 , Pages 2672-2677 ; 21578095 (ISSN); 9781538682098 (ISBN) ; Maddah Ali, M. A ; IEEE Information Theory Society; The Institute of Electrical and Electronics Engineers ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Sharding, i.e. splitting the miners or validators to form and run several subchains in parallel, is known as one of the main solutions to the scalability problems of blockchains. The drawback is that as the number of miners expanding each subchain becomes small, it becomes vulnerable to security attacks. To solve this problem, a framework, named as Ployshard, has been proposed in which each validator verifies a coded combination of the blocks introduced by different subchains, thus helping to protect the security of all subchains. In this paper, we introduce an attack on Ployshard, called the discrepancy attack, which is the result of malicious nodes controlling a few subchains and...
Optical pattern generator for efficient bio-data encoding in a photonic sequence comparison architecture
, Article PLoS ONE ; Volume 16, Issue 1 , 2021 ; 19326203 (ISSN) ; Dijujin, N. H ; Koohi, S ; Sharif University of Technology
Public Library of Science
2021
Abstract
In this study, optical technology is considered as SA issues’ solution with the potential ability to increase the speed, overcome memory-limitation, reduce power consumption, and increase output accuracy. So we examine the effect of bio-data encoding and the creation of input images on the pattern-recognition error-rate at the output of optical Vander-lugt correlator. Moreover, we present a genetic algorithm-based coding approach, named as GAC, to minimize output noises of cross-correlating data. As a case study, we adopt the proposed coding approach within a correlation-based optical architecture for counting k-mers in a DNA string. As verified by the simulations on Salmonella whole-genome,...
Optical pattern generator for efficient bio-data encoding in a photonic sequence comparison architecture
, Article PloS one ; Volume 16, Issue 1 , 2021 , Pages e0245095- ; 19326203 (ISSN) ; Hashemi Dijujin, N ; Koohi, S ; Sharif University of Technology
NLM (Medline)
2021
Abstract
In this study, optical technology is considered as SA issues' solution with the potential ability to increase the speed, overcome memory-limitation, reduce power consumption, and increase output accuracy. So we examine the effect of bio-data encoding and the creation of input images on the pattern-recognition error-rate at the output of optical Vander-lugt correlator. Moreover, we present a genetic algorithm-based coding approach, named as GAC, to minimize output noises of cross-correlating data. As a case study, we adopt the proposed coding approach within a correlation-based optical architecture for counting k-mers in a DNA string. As verified by the simulations on Salmonella whole-genome,...
Optical pattern generator for efficient bio-data encoding in a photonic sequence comparison architecture
, Article PLoS ONE ; Volume 16, Issue 1 January 2021 , 2021 ; 19326203 (ISSN) ; Dijujin, N. H ; Koohi, S ; Sharif University of Technology
Public Library of Science
2021
Abstract
In this study, optical technology is considered as SA issues’ solution with the potential ability to increase the speed, overcome memory-limitation, reduce power consumption, and increase output accuracy. So we examine the effect of bio-data encoding and the creation of input images on the pattern-recognition error-rate at the output of optical Vander-lugt correlator. Moreover, we present a genetic algorithm-based coding approach, named as GAC, to minimize output noises of cross-correlating data. As a case study, we adopt the proposed coding approach within a correlation-based optical architecture for counting k-mers in a DNA string. As verified by the simulations on Salmonella whole-genome,...
Optical pattern generator for efficient bio-data encoding in a photonic sequence comparison architecture
, Article PloS one ; Volume 16, Issue 1 , 2021 , Pages e0245095- ; 19326203 (ISSN) ; Hashemi Dijujin, N ; Koohi, S ; Sharif University of Technology
NLM (Medline)
2021
Abstract
In this study, optical technology is considered as SA issues' solution with the potential ability to increase the speed, overcome memory-limitation, reduce power consumption, and increase output accuracy. So we examine the effect of bio-data encoding and the creation of input images on the pattern-recognition error-rate at the output of optical Vander-lugt correlator. Moreover, we present a genetic algorithm-based coding approach, named as GAC, to minimize output noises of cross-correlating data. As a case study, we adopt the proposed coding approach within a correlation-based optical architecture for counting k-mers in a DNA string. As verified by the simulations on Salmonella whole-genome,...
Gellan gel comprising short PVDF based-nanofibers: the effect of piezoelectric nanofiber on the mechanical and electrical behavior
, Article Materials Today Communications ; 2020 ; Ramazani Saadat Abadi, A ; Shirazi, F. H ; Hassanzadeh Nemati, N ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Gel-fiber structure with the potential of extracellular matrix (ECM) mimics can be introduced as a suitable candidate for bioengineering applications. In this study, piezoelectric gellan gel-fiber was prepared with incorporating poly(vinylidenefluoride) (PVDF)/glass-flake in the gellan matrix. Glass-flake nanoparticles were modified with silane group, PVDF/glass-flake nanofibers were synthesized and short-strand nanofibers were fabricated using the mechanical homogenizer method. Brunauer–Emmett–Teller (BET), Fourier-transform infrared spectroscopy (FTIR), and Thermogravimetric analysis (TGA) analyses were used for surface modification study, and scanning electron microscopy (SEM),...
Optimization of nonlinear unbalanced flexible rotating shaft passing through critical speeds
, Article International Journal of Structural Stability and Dynamics ; Volume 22, Issue 1 , 2022 ; 02194554 (ISSN) ; Rokn Abadi, M ; Firouz Abadi, R. D ; Sharif University of Technology
World Scientific
2022
Abstract
This work studies the nonlinear oscillations of an elastic rotating shaft with acceleration to pass through the critical speeds. A mathematical model incorporating the Von-Karman higher-order deformations in bending is developed to investigate the nonlinear dynamics of rotors. A flexible shaft on flexible bearings with springs and dampers is considered as rotor system for this work. The shaft is modeled as a beam and the Euler-Bernoulli beam theory is applied. The kinetic and strain energies of the rotor system are derived and Lagrange method is then applied to obtain the coupled nonlinear differential equations of motion for 6 degrees of freedom. In order to solve these equations...
Nonlinear responses of unbalanced flexible rotating shaft passing through critical speeds
, Article Meccanica ; 2021 ; 00256455 (ISSN) ; Rokn Abadi, M ; Firouz Abadi, R.D ; Mehralian, F ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
This work studies the nonlinear oscillations of an elastic rotating shaft with acceleration to pass through the critical speeds. A mathematical model incorporating the Von-Karman higher-order deformations in bending is developed and analyzed to investigate the nonlinear dynamics of rotors. A flexible shaft on flexible bearings with springs and dampers is considered as rotor system for the present work. The shaft is modeled as a beam with a circular cross-section and the Euler Bernoulli beam theory is applied. The kinetic and strain energies of the rotor system are derived and Lagrange method is then applied to obtain the coupled nonlinear differential equations of motion for 6° of freedom....
Nonlinear responses of unbalanced flexible rotating shaft passing through critical speeds
, Article Meccanica ; Volume 57, Issue 1 , 2022 , Pages 193-212 ; 00256455 (ISSN) ; Rokn Abadi, M ; Firouz Abadi, R. D ; Mehralian, F ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
This work studies the nonlinear oscillations of an elastic rotating shaft with acceleration to pass through the critical speeds. A mathematical model incorporating the Von-Karman higher-order deformations in bending is developed and analyzed to investigate the nonlinear dynamics of rotors. A flexible shaft on flexible bearings with springs and dampers is considered as rotor system for the present work. The shaft is modeled as a beam with a circular cross-section and the Euler Bernoulli beam theory is applied. The kinetic and strain energies of the rotor system are derived and Lagrange method is then applied to obtain the coupled nonlinear differential equations of motion for 6° of freedom....
Nanotechnology in the public eye: The case of Iran, as a developing country
, Article Journal of Nanoparticle Research ; Volume 13, Issue 8 , 2011 , Pages 3511-3519 ; 13880764 (ISSN) ; Sadrnezhaad, S. K ; Nejad, N. M ; Mahmoodi, M ; Ibrahimi Ghavam Abadi, L ; Sharif University of Technology
2011
Abstract
Using survey data, public awareness of and attitudes toward nanotechnology are examined in Iran (N ≥ 759). Iran is a developing country with a national nanotechnology action plan for a ten year period starting from 2003 and has been active in the field of research and development of nanotechnology meanwhile. First, the results show that majority of people are still not familiar with nanotechnology and perceived risks posed by this technology are not considered to be a lot and most people feel its benefits outweigh the risks. The emotions toward this technology are of a hopeful and positive nature and this technology is looked upon favorably in Iran. In particular, our results reveals that...
Observation of cosmic rays by Alborz -1 array
, Article Iranian Journal of Physics Research ; Volume 17, Issue 3 , 2017 , Pages 473-484 ; 16826957 (ISSN) ; Sharif University of Technology
Isfahan University of Technology
2017
Abstract
The first phase of the Alborz Observatory Array (Alborz-1) consists of 20 plastic scintillation detectors each one with surface area of 0.25 m2 spread over an area of 40×40 m2 realized to the study of Extensive Air Showers around the knee at the Sharif University of Technology campus. The first stage of the project including construction and operation of a prototype system has now been completed and the electronics that will be used in the array instrument has been tested under field conditions. In order to achieve a realistic estimate of the array performance, a large number of simulated CORSIKA showers have been used. In the present work, theoretical results obtained in the study of...
Analysis of Nano Particles Application in Perfprmance of Polysulfone Fuel Cell Membrane
, M.Sc. Thesis Sharif University of Technology ; Ramezani saadat abadi, Ahmad (Supervisor) ; Mousavi, Abbass (Supervisor)
Abstract
Today, energy crises and the environmental pollution have become serious problems for the human being. To address these problems, extensive efforts have been made to replace fossil fuels with other clean energy resources such as fuel cells. In the meantime, polymer electrolyte fuel cells are very important as they are now commonly used in the field of transportation, and their importance become even more obvious as we consider the fact that the by-products from electricity production by such cells are simply water and heat. This research studies the efficiency of the polymer called “polysulfone” as an electrolyte fuel cell, which has the above named mechanical thermal and chemical...
A procedure for obtaining a behavioral description for the control logic of a non-linear pipeline
, Article Proceedings of the ASP - DAC 2004 Asia and South Pacific Design Automation Conference - 2004, Yokohama, 27 January 2004 through 30 January 2004 ; 2004 , Pages 86-91 ; Sharif University of Technology
2004
Abstract
Much attention has been directed to different aspects of the design of pipelines. Design of the control logic of non-linear pipelines has however, been considered as a subsidiary issue in that an RTL description for such logic can easily be obtained from a behavioral description, with the use of widely available synthesis tools. But, as the complexity of a non-linear pipeline increases, so does the complexity of the control logic. The complexity may be to an extent that obtaining even a behavioral description for the control logic is rendered difficult. This paper focuses on further automating the development of systems consisting of non-linear or multi-function pipelines by proposing an...
Nonlinear Behavior of Short Structures under Column Displacement Effect
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
Nowadays, according to increasing development of construction industry in the world especially in the building area, the need to use technology and innovation for fabrication and maintenance of this industry has increased. And this fact becomes apparent that the use of traditional systems of construction isn’t tailored the countries’ requirements anymore. One of the construction industry’s limitations is the restrictions on architectural designs reys. The columns are among the most important components of structure and have a major role in bearing all gravity and lateral loads and transferring them to the foundation. The failure or destruction of the components in the structure under applied...
Magnetoelastic instability of a long graphene nano-ribbon carrying electric current
, Article Advances in Applied Mathematics and Mechanics ; Vol. 6, issue. 3 , 2014 , pp. 299-306 ; ISSN: 20700733 ; Mohammadkhani, H ; Sharif University of Technology
2014
Abstract
This paper aims at investigating the resonance frequencies and stability of a long Graphene Nano-Ribbon (GNR) carrying electric current. The governing equation of motion is obtained based on the Euler-Bernoulli beam model along with Hamilton's principle. The transverse force distribution on the GNR due to the interaction of the electric current with its own magnetic field is determined by the Biot-Savart and Lorentz force laws. Using Galerkin's method, the governing equation is solved and the effect of current strength and dimensions of the GNR on the stability and resonance frequencies are investigated
Resonance frequencies and stability of two flexible permanent magnetic beams facing each other
, Article Journal of Sound and Vibration ; Volume 331, Issue 26 , 2012 , Pages 5745-5754 ; 0022460X (ISSN) ; Mohammadkhani, H ; Sharif University of Technology
2012
Abstract
This paper aims at investigating the interaction of two flexible permanent magnet beams facing each other. The governing equations of motion are obtained based on the Euler-Bernoulli beam model along with Hamiltons principle. Assuming that the beams tips are far enough, each magnet beam is considered as a series of dipole segments and the external force and moment distributions over each beam due to the magnetic field of the other one is calculated in the deformed configuration. The transverse deflections of the beams are written as series expansions of the mode shapes of an unloaded cantilever beam and the Galerkin method is applied to determine the stability and resonance frequencies....