Loading...
Search for:
rad--a
0.006 seconds
Synchronizability of dynamical networks: different measures and coincidence
, Article International Journal of Nonlinear Sciences and Numerical Simulation ; Volume 10, Issue 11-12 , 2009 , Pages 1481-1489 ; 15651339 (ISSN) ; Ajdari Rad, A ; Sharif University of Technology
Abstract
In this paper, we list four different interpretations of synchronizability, study their profile in different network structures and give evidence that they do not coincide, in general. By changing the network topological properties, their behavior is tracked and compared with each other. It is shown that their trend goes in different directions in heterogeneous networks such as scale-free ones, whereas in homogeneous ones such as random networks they go hand in hand, as networks' structural parameters change. We also consider networks whose synchronization properties are enhanced through proper weighting or rewiring. The weighting procedure considers information on the node-degrees, node and...
Plant-wide simulation model for modified claus process based on simultaneous data reconciliation and parameter estimation
, Article Chemical Engineering Transactions ; Volume 57 , 2017 , Pages 997-1002 ; 22839216 (ISSN); 9788895608488 (ISBN) ; Rad, A ; Sharif University of Technology
Italian Association of Chemical Engineering - AIDIC
2017
Abstract
The modified Claus process is characterized by several problems, namely poor instrumentation and no precise kinetic model for predicting the behaviour of the reactors. Using operational data of an industrial plant, this paper proposes a general framework for development of a plant-wide simulation model for modified Claus process based on simultaneous data reconciliation and parameter estimation (DRPE) using Genetic algorithm (GA). HYSYS as a commercial process simulator that provides a high-level of accuracy as well as redundancy which all is favoured for DRPE has been utilized in this work. Building a communication framework between HYSYS and MATLAB, data pre-processing of raw measurement...
Rewirings based on the eigenvectors of the laplacian matrix for enhancing synchronizability of dynamical networks
, Article 2009 7th IEEE International Conference on Industrial Informatics, INDIN 2009, Cardiff, 23 June 2009 through 26 June 2009 ; 2009 , Pages 588-593 ; 19354576 (ISSN); 9781424437603 (ISBN) ; Ajdari Rad, A ; Sharif University of Technology
2009
Abstract
Synchronizability of dynamical networks can be defined as the ease by which the network synchronizes its activity. We propose a method for enhancing the synchronizability of dynamical networks by efficient rewirings. The method is based on the eigenvectors corresponding to the second smallest and the largest eigenvalue of the Laplacian matrix and a modified version of the simulated annealing approach is used to perform the optimization task. Starting from a simple network, i.e. an undirected and unweighted network, and at each step, an edge is selected for disconnection and two non-adjacent nodes for creating at edge in between. The effectiveness of the algorithm is tested on artificially...
Adaptive model predictive TCP delay-based congestion control
, Article Computer Communications ; Volume 29, Issue 11 , 2006 , Pages 1963-1978 ; 01403664 (ISSN) ; Mohsenian Rad, A. H ; Sharif University of Technology
2006
Abstract
Adaptive Model Predictive Transmission Control Protocol (AMP-TCP) as a new TCP delay-based congestion control algorithm is introduced. Both aspects of design and implementation of the algorithm are described using simulations on the ns-2 network simulator. The design stage is composed of two steps. First, a recursive system identification approach is proposed to capture the network delay dynamics from TCP source view. Second, the proposed modeling is employed to develop an adaptive model predictive TCP congestion control strategy in the absence of any explicit congestion notification. The characteristics and performance of AMP-TCP are investigated using several network simulations. Finally a...
TCP retransmission timer adjustment mechanism using model-based RTT predictor
, Article 2004 5th Asian Control Conference, Melbourne, 20 July 2004 through 23 July 2004 ; Volume 1 , 2004 , Pages 686-693 ; 0780388739 (ISBN) ; Mohsenian Rad, A. H ; Sharif University of Technology
2004
Abstract
Transmission Control Protocol (TCP) uses multiple timers to do its work. The most important of these is the retransmission timer. In this paper, the TCP retransmission timer adjustment mechanism is approached from a system point of view and a new mechanism is proposed. A simple recursive system identification algorithm is used to capture both time variant and time invariant Internet behavior. Also a dynamic model-based Round-Trip Time (RTT) predictor was provided. Based on network simulation and real Internet data collection, it was observed that when the retransmission timer is adjusted by the proposed predictor instead of the traditional RTT estimator, performance increased significantly
Investigation of the Shaft Failure Connected to Extruder
, Article Journal of Failure Analysis and Prevention ; Volume 15, Issue 6 , 2015 , Pages 775-781 ; 15477029 (ISSN) ; Mashayekhi, F ; Movahedi-Rad, A ; Sharif University of Technology
Springer New York LLC
2015
Abstract
In this study, the failure analysis of a shaft of a unit, which had been failed during the service, was studied. This shaft was welded to the blades, and their chemical compositions were determined by spectroscopy method. In order to determine the root cause of failure and contribution factors, different investigation methods including visual examination, optical microscopy and scanning electron microscope analysis, and hardness test were carried out. It was concluded that the shaft was failed due to fatigue. The failure was caused by improper welding of blades to the shaft. At the end, in order to prevent or decelerate such failure, some recommended remedies were suggested
Water-based sol-gel nanocrystalline barium titanate: Controlling the crystal structure and phase transformation by Ba:Ti atomic ratio
, Article Journal of Materials Science ; Volume 44, Issue 18 , 2009 , Pages 4959-4968 ; 00222461 (ISSN) ; Esmaeili Rad, A ; Fray, D. J ; Sharif University of Technology
2009
Abstract
Highly stable, water-based barium titanate (BaTiO3) sols were developed by a low cost and straightforward sol-gel process. Nanocrystalline barium titanate thin films and powders with various Ba:Ti atomic ratios were produced from the aqueous sols. The prepared sols had a narrow particle size distribution in the range 21-23 nm and they were stable over 5 months. X-ray diffraction pattern revealed that powders contained mixture of hexagonal- or perovskite-BaTiO3 as well as a trace of Ba2Ti 13O22 and Ba4Ti2O27 phases, depending on annealing temperature and Ba:Ti atomic ratio. Highly pure barium titanate with cubic perovskite structure achieved with Ba:Ti = 50:50 atomic ratio at the high...
A risk-based decision making approach to determine fireproofing requirements against jet fires
, Article Journal of Loss Prevention in the Process Industries ; Volume 26, Issue 4 , 2013 , Pages 771-781 ; 09504230 (ISSN) ; Rad, A ; Kareshki, H ; Abdolhamidzadeh, B ; Parvizsedghy, R ; Rashtchian, D ; Sharif University of Technology
2013
Abstract
API Publication 2218 is one of the most referred practices for fireproofing of onshore structural supports. Despite the extensive citation, it solely considers the effects of pool fire and rarely addresses jet fire outcomes. This absence of an explicit approach is common among all the other major references. Therefore, the basic objective of this paper is to introduce a new approach for determination of the necessity for fireproofing of structural supports against jet fires. For this purpose, the flame geometry and duration of jet fires are simulated for different leak sizes in identified fire potential sources. Then, following a worst-case analysis, those structures that may be impinged by...
Solid supported microwave-assisted Beckmann rearrangement of ketoximes in dry media
, Article Synthetic Communications ; Volume 34, Issue 11 , 2004 , Pages 2071-2075 ; 00397911 (ISSN) ; Rastegar Rad, A. A ; Zali-Boinee, H ; Sharif University of Technology
2004
Abstract
An AlCl3-ZnCl2 mixture supported on silica gel is found to be a new efficient medium for the Beckmann rearrangement in solvent-free conditions under microwave irradiation. The yields are good to excellent
TCP retransmission timer adjustment mechanism using system identification
, Article Proceedings of the 2004 American Control Conference (AAC), Boston, MA, 30 June 2004 through 2 July 2004 ; Volume 3 , 2004 , Pages 2328-2332 ; 07431619 (ISSN); 0780383354 (ISBN) ; Rad, A. H. M ; American Automatic Control Council; International Federation of Automation Control, IFAC ; Sharif University of Technology
2004
Abstract
In this paper, the TCP retransmission timer adjustment mechanism is approached from the system's theoretic point of view. TCP uses a simple recursive system identification algorithm to capture both time variant and time invariant Internet behavior and provides a dynamic Round-Trip Time (RTT) predictor. Based on real Internet data collection, it is observed that when the retransmission timer is adjusted by using the proposed predictor instead of the traditional RTT estimator, its performance increases significantly
Magnetic CoFe2O4 nanoparticles doped with metal ions: A review
, Article Ceramics International ; Volume 46, Issue 11 , 2020 , Pages 18391-18412 ; Moradi, M ; Parvin, N ; Nemati, A ; Jafari Rad, A ; Sheysi, N ; Abouchenari, A ; Mohammadi, A ; Karbasi, S ; Ahmadi, Z ; Esmaeilkhanian, A ; Irani, M ; Pakseresht, A ; Sahmani, S ; Shahedi Asl, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Ceramic-magnetic nanoparticles (CMNPs) are attracting attention due to their various applications, especially in biomedical industries. Among them, spinel ferrite CMNPs have received considerable deliberations among different spinel metal oxides due to their fascinating characteristics. Spinel ferrite CMNPs are used for enhancement of the applicability of CMNPs without affecting the intrinsic advantages of iron oxide CMNPs. Spinel ferrites with doping agents have useful electrical and magnetic properties in various fields. Moreover, the replacement of metallic atoms in ferrites is promising to manipulate physical characteristics and improve their performance. Among different spinel ferrites,...
Channelopathy-related SCN10A gene variants predict cerebellar dysfunction in multiple sclerosis
, Article Neurology ; Volume 86, Issue 5 , 2016 , Pages 410-417 ; 00283878 (ISSN) ; Sadaghiani, S ; Park, M. T. M ; Mashhadi, R ; Nazeri, A ; Noshad, S ; Salehi, M. J ; Naghibzadeh, M ; Moghadasi, A. N ; Owji, M ; Doosti, R ; Hashemi Taheri, A. P ; Rad, A. S ; Azimi, A ; Chakravarty, M. M ; Voineskos, A. N ; Nazeri, A ; Sahraian, M. A ; Sharif University of Technology
Lippincott Williams and Wilkins
Abstract
Objective: To determine the motor-behavioral and neural correlates of putative functional common variants in the sodium-channel NaV1.8 encoding gene (SCN10A) in vivo in patients with multiple sclerosis (MS). Methods: We recruited 161 patients with relapsing-onset MS and 94 demographically comparable healthy participants. All patients with MS underwent structural MRI and clinical examinations (Expanded Disability Status Scale [EDSS] and Multiple Sclerosis Functional Composite [MSFC]). Whole-brain voxel-wise and cerebellar volumetry were performed to assess differences in regional brain volumes between genotype groups. Resting-state fMRI was acquired from 62 patients with MS to evaluate...