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Tunable spatial fractional derivatives with graphene-based transmit arrays
, Article Optics Express ; Volume 31, Issue 8 , 2023 , Pages 12572-12584 ; 10944087 (ISSN) ; Habibiyan, H ; Khavasi, A ; Sharif University of Technology
Optica Publishing Group (formerly OSA)
2023
Abstract
The optical implementation of mathematical spatial operators is a critical step toward achieving practical high-speed, low-energy analog optical processors. In recent years, it has been shown that using fractional derivatives in many engineering and science applications leads to more accurate results. In the case of optical spatial mathematical operators, the derivatives of the first and second orders have been investigated. But no research has been performed on fractional derivatives. On the other hand, in previous studies, each structure is dedicated to a single integer order derivative. This paper proposes a tunable structure made of graphene arrays on silica to implement fractional...
KDeep: a new memory-efficient data extraction method for accurately predicting DNA/RNA transcription factor binding sites
, Article Journal of Translational Medicine ; Volume 21, Issue 1 , 2023 ; 14795876 (ISSN) ; Tabatabaei, F ; Koohi, S ; Sharif University of Technology
BioMed Central Ltd
2023
Abstract
This paper addresses the crucial task of identifying DNA/RNA binding sites, which has implications in drug/vaccine design, protein engineering, and cancer research. Existing methods utilize complex neural network structures, diverse input types, and machine learning techniques for feature extraction. However, the growing volume of sequences poses processing challenges. This study introduces KDeep, employing a CNN-LSTM architecture with a novel encoding method called 2Lk. 2Lk enhances prediction accuracy, reduces memory consumption by up to 84%, reduces trainable parameters, and improves interpretability by approximately 79% compared to state-of-the-art approaches. KDeep offers a promising...
An accurate alignment-free protein sequence comparator based on physicochemical properties of amino acids
, Article Scientific Reports ; Volume 12, Issue 1 , 2022 ; 20452322 (ISSN) ; Abdosalehi, A. S ; Pouyamehr, F ; Koohi, S ; Sharif University of Technology
Nature Research
2022
Abstract
Bio-sequence comparators are one of the most basic and significant methods for assessing biological data, and so, due to the importance of proteins, protein sequence comparators are particularly crucial. On the other hand, the complexity of the problem, the growing number of extracted protein sequences, and the growth of studies and data analysis applications addressing protein sequences have necessitated the development of a rapid and accurate approach to account for the complexities in this field. As a result, we propose a protein sequence comparison approach, called PCV, which improves comparison accuracy by producing vectors that encode sequence data as well as physicochemical properties...
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....
Investigation of properties of polyethylene/clay nanocomposites prepared by new in situ ziegler-natta catalyst
, Article Materials and Design ; Volume 30, Issue 7 , 2009 , Pages 2309-2315 ; 02641275 (ISSN) ; Ramazani Saadat Abadi, A ; Baniasadi, H ; Tavakolzadeh, F ; Sharif University of Technology
2009
Abstract
This paper is devoted to investigation of morphological and physical-mechanical properties of polyethylene (PE)/clay nanocomposites prepared via in situ polymerization method using bi-supported Ziegler-Natta catalyst. Bentonite type clay and MgCl2 (ethoxide type) were used as the support of TiCl4. Catalyst support and polymerization process have been done in slurry phase using Triisobutylaluminum as the co-catalyst. The microstructure of the nanocomposites was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM indicated that almost fully exfoliated PE/clay nanocomposites were produced successfully using this method. According to permeability...
In situ emulsion polymerization and characterization of PVAc nanocomposites including colloidal silica nanoparticles for wood specimens bonding
, Article Journal of Applied Polymer Science ; Volume 137, Issue 15 , 2020 ; Ramezani Saadat Abadi, A ; Haddadi, S. A ; Ghaderi, S ; Azamian, F ; Sharif University of Technology
John Wiley and Sons Inc
2020
Abstract
Polyvinyl acetate (PVAc) nanocomposites for wood adhesives containing different amounts of colloidal silica nanoparticles (CSNs) were synthesized via in situ one-step emulsion polymerization. The adhesion strength of wood specimens bonded by PVAc nanocomposites was investigated by the tensile test. Thermal properties of PVAc nanocomposites were also characterized by differential scanning calorimetry and thermogravimetric analysis. Rheological and morphological properties of the PVAc nanocomposites were investigated using rheometric mechanical spectrometry and field emission scanning electron microscopy (FESEM), respectively. The obtaining results showed that the shear strength of PVAc...
A new method for free vibration analysis of nanobeams: Introduction of equivalent lattice stiffness method
, Article Solid State Communications ; Volume 287 , 2019 , Pages 35-42 ; 00381098 (ISSN) ; Mehralian, F ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Since the efficiency of non-classical continuum theories is strongly dependent on the recognition of the suitable values of small length scale parameters and there is still uncertainty about them, a novel approach, equivalent lattice stiffness method is developed here. This approach without the characteristic length scale parameter which arises in non-classical continuum theories, such as nonlocal theory and strain gradient theory, is capable to capture size effect more easily and accurately. This method is proposed based on the concept of lattice dynamics but a Taylor series expansion is involved to approximate the displacements of the continuous domain; accordingly, this approach is in...
A new method for free vibration analysis of nanobeams: Introduction of equivalent lattice stiffness method
, Article Solid State Communications ; Volume 287 , 2019 , Pages 35-42 ; 00381098 (ISSN) ; Mehralian, F ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Since the efficiency of non-classical continuum theories is strongly dependent on the recognition of the suitable values of small length scale parameters and there is still uncertainty about them, a novel approach, equivalent lattice stiffness method is developed here. This approach without the characteristic length scale parameter which arises in non-classical continuum theories, such as nonlocal theory and strain gradient theory, is capable to capture size effect more easily and accurately. This method is proposed based on the concept of lattice dynamics but a Taylor series expansion is involved to approximate the displacements of the continuous domain; accordingly, this approach is in...
A size-dependent generalized thermoelasticity theory for thermoelastic damping in vibrations of nanobeam resonators
, Article International Journal of Structural Stability and Dynamics ; Volume 23, Issue 12 , 2023 ; 02194554 (ISSN) ; Saleh, Z. M ; Imran, A. F ; Yasin, Y ; Ruhaima, A. A. K ; Gatea, M. A ; Esmaeili, S ; Sharif University of Technology
World Scientific
2023
Abstract
Thermoelastic damping (TED) has been discerned as a definite source of intrinsic energy loss in miniaturized mechanical elements. The size-dependent structural and thermal behavior of these small-sized structures has been proven through experimental observations. As a first attempt, this article exploits nonlocal strain gradient theory (NSGT) and nonlocal dual-phase-lag (NDPL) heat conduction model simultaneously to acquire a mathematical formulation and analytical solution for TED in nanobeams that can accommodate size effect into both structural and heat transfer fields. For this purpose, the coupled equations of motion and heat conduction are firstly extracted via NSGT and NDPL model....
Utilising flags to reduce drag around a short finite circular cylinder
, Article Journal of Turbulence ; Volume 19, Issue 3 , 2018 , Pages 229-251 ; 14685248 (ISSN) ; Kiani, F ; Tahaye Abadi, M ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
This paper utilises flags to decrease the drag around a short finite circular cylinder. Wall-adapted large eddy simulation and two-way fluid–structure interaction methods were applied to resolve unsteady turbulent flow structure. The far-field Reynolds number of the current configuration based on the cylinder diameter was chosen to be 20,000. In addition, the length-to-diameter ratio of the cylinder was assumed to be L/D = 2 whereas the flexible flag had a width-to-diameter ratio of W/D = 1.5. The results were compared with the regular short finite circular cylinder and the rigid flagged cylinder in our previous work. The results indicate that utilising flags inside the near-wake region of...
A nine-step approach for developing and implementing an “agricultural drought risk management plan”; case study: Alamut River basin in Qazvin, Iran
, Article Natural Hazards ; Volume 102, Issue 3 , 2020 , Pages 1187-1205 ; Hosseini Hossein Abadi, F ; Sharif University of Technology
Springer
2020
Abstract
Occurrence of drought, as an inevitable natural climate feature, cannot be ceased while happening. However, costs of the consequences could be alleviated using mature scientific integrated approaches. To reduce the amount of damage, it is required to provide “Contingency” and “Mitigation” action plans. For this reason, development of efficient operating instructions for various regions based on weather conditions and field studies is needed as well as having a sophisticated understanding of socioeconomic situations. This paper describes an approach to provide the first national agricultural drought risk management plan for a river basin in Iran country as a pilot. The study lasted for...
HELIOS: High-speed sequence alignment in optics
, Article PLoS Computational Biology ; Volume 18, Issue 11 , 2022 ; 1553734X (ISSN) ; Akbari Rokn Abadi, S ; Koohi, S ; Sharif University of Technology
Public Library of Science
2022
Abstract
In response to the imperfections of current sequence alignment methods, originated from the inherent serialism within their corresponding electrical systems, a few optical approaches for biological data comparison have been proposed recently. However, due to their low performance, raised from their inefficient coding scheme, this paper presents a novel all-optical high-throughput method for aligning DNA, RNA, and protein sequences, named HELIOS. The HELIOS method employs highly sophisticated operations to locate character matches, single or multiple mutations, and single or multiple indels within various biological sequences. On the other hand, the HELIOS optical architecture exploits...
An automated ultra-fast, memory-efficient, and accurate method for viral genome classification
, Article Journal of Biomedical Informatics ; Volume 139 , 2023 ; 15320464 (ISSN) ; Mohammadi, A ; Koohi, S ; Sharif University of Technology
Academic Press Inc
2023
Abstract
The classification of different organisms into subtypes is one of the most important tools of organism studies, and among them, the classification of viruses itself has been the focus of many studies due to their use in virology and epidemiology. Many methods have been proposed to classify viruses, some of which are designed for a specific family of organisms and some of which are more general. But still, especially for certain categories such as Influenza and HIV, classification is facing performance challenges as well as processing and memory bottlenecks. In this way, we designed an automated classifier, called PC-mer, that is based on k-mer and physicochemical characteristics of...
Synthesis and characterization of poly(L-lactide)-block-poly(ε-caprolactone)-grafted titanium dioxide nanoparticles via ring-opening in situ grafting polymerization
, Article Polymer Composites ; Volume 42, Issue 8 , 2021 , Pages 3722-3731 ; 02728397 (ISSN) ; Sharif, F ; Ramezani Saadat Abadi, A ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
The synthesis of nanocomposites via in situ grafting polymerization due to its ability to produce polymeric materials with promising microscopic and macroscopic characteristics is becoming very attractive. In this paper, different poly(L-Lactide)-block-poly(ε-caprolactone) (PLLA-b-PCL) copolymers were in situ synthesized in the presence of modified titanium dioxide (TiO2) nanoparticles (mTNP) as the initiator and stannous octoate as the catalyst. The surface of TiO2 was modified by grafting aminopropyl trimethoxy silane to improve initiator efficiency. Copolymers with 90/10, 70/30, and 50/50 mass ratio of L-lactide/ ε-caprolactone and 5 wt% of mTNP (proportional to ε-caprolactone) were...
O-TF and O-FTF, optical fault-tolerant DCNS
, Article Proceedings - 26th Euromicro International Conference on Parallel, Distributed, and Network-Based Processing, PDP 2018 ; 6 June , 2018 , Pages 639-642 ; 9781538649756 (ISBN) ; Koohi, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Performance of a data center is a function of three features; bandwidth, latency, and reliability. By adopting optical technology in data center network, bandwidth increment, in addition to reduction of transmission latency and power consumption, is achieved. Unfortunately, fault tolerance of the optical networks has raised less attention so far. So in this paper, we propose a fault-tolerant, scalable, and high-performance optical architecture built upon previously proposed O-TF network, with the goal of redundancy optimization and reducing the minimum number of wavelength channels required for non-blocking functionality of the network. Moreover, reducing network diameter, in O-FTF network...
Exploitation of wavelength, hardware, and path redundancies in fault-tolerant all-optical DCNs
, Article Optical Fiber Technology ; Volume 51 , 2019 , Pages 77-89 ; 10685200 (ISSN) ; Koohi, S ; Sharif University of Technology
Academic Press Inc
2019
Abstract
Data center performance is affected by three main factors; bandwidth, latency, and reliability of intra-data center interconnection network. Bandwidth and latency are definitely improved by adopting optical technology for intra-data center communication, but fault tolerance of the corresponding optical networks has been raised less. Recently, we introduced two Torus-based, all-optical, and non-blocking networks, i.e. O-TF and O-FTF, addressing reliability of optical networks, and now, in this paper, to address the scalability problem, we propose a novel Optical Clos-based architecture which reduces minimum number of required wavelength channels, as well as, the switch size in each node....
Processing Queries with Mathematical Expressions on Encrypted Outsourced Databases
, M.Sc. Thesis Sharif University of Technology ; Jalil, Rasool (Supervisor)
Abstract
The ever-increasing volume of data and the lack of computational and storage facilities have caused a managerial challenge to organizations. The existence of these challenges on the one hand and the increase of storage services on the other hand have compelled the organizations to delegate their storage and management of data to the server providers of cloud storage services. The outsourcing of data to servers obviates the need for purchasing exorbitant storage equipment and recruiting professional workforce in the organization. Since the organization’s data will be kept outside the organization’s ambience in case of using such services in form of outsourcing, and the data will not be under...
A numerical investigation on the free vibration of carbon nanopeapods as variable frequency beam resonators
, Article Modern Physics Letters B ; Volume 27, Issue 21 , August , 2013 ; 02179849 (ISSN) ; Alavi, S. M ; Sharif University of Technology
2013
Abstract
This study aims at investigation of the resonance frequencies of carbon nanopeapods constructed by a single wall carbon nanotube and encapsulated buckyball molecules (C60). A nanopeapod can be used as a nanoscale variable frequency beam resonator according to the number and positions of the encapsulated fullerenes. Using the molecular structural mechanics method the covalence bonds are simulated by equivalent beam elements and the van der Waal interactions between the buckyballs and nanotube are modeled as linear springs. Also, an equivalent beam model is proposed for the nanopeapod with sectional properties which are obtained by the molecular structural mechanics model. The beam-like modes...
Dynamic Functional Connectivity in Autism Spectrum Disorder Using Resting-State fMRI
, M.Sc. Thesis Sharif University of Technology ; Fatemizadeh, Emadeddin (Supervisor)
Abstract
Autism Spectrum Disorder (ASD) is a group of neurodevelopmental disorders that cause repetitive behaviors and social and communication skills abnormalities. Autistic Disorder(AD) is one of the disorders in ASD that is being investigated in this study. There has been an increase in research about AD in recent years due to the increasing AD prevalence and the high autistic living costs. The dynamic functional connectivity between healthy and autistic groups has been analyzed by using graph theory. The brain is modeled as a dynamic graph using resting-state fMRI. The graph theory metric is calculated in the dynamic graph of each subject, and the distinction of the two groups is checked using...