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jahanian-najafabadi--hamid
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Total 969 records
New Engine Bay Design For IRAN-140 Aircraft's Auxiliary Power Unit by Damage Tolerance Theory
, M.Sc. Thesis Sharif University of Technology ; Adib Nazari, Saeed (Supervisor)
Abstract
Different reasons, all structures have inside crack or surface crack when crack growth is more at the frequancy load and it is one of the main factor in the diagnosis of structural life that this sensitivity is much greater aerial parts industry. The aim of this project, designing a new structure for the auxiliary engine compartment of the aircraft with the damage tolerance theory for cargo aircraft within the country are making. In the first stage after reviewing activitation past, the evaluation design rules between each company design its obligations, standards in design and then conceptual plan to make. Then reload force plan to make. At this stage with regard to maneuver the airplane...
Dynamic Hand Gesture Recognition Using Bag of Words
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
New applications of gesture recognition problem have emerged that are constrained by lack of sufficient training data. Bag-of-words methods are attractive in this type of scenario and have come to attention again. A typical bagof-words system has four stages: feature extraction, dictionary learning and feature coding, pooling, and classification. The dictionary learning and feature coding stage is important due to its effect on classifier complexity and the discriminative capability of the features that affect the final result. Existing methods in gesture recognition have neglected the relation between different gestures when learning a dictionary. In this thesis, we focus on the relations...
Sparse Recovery in Peer to Peer Networks via Compressive Sensing
, M.Sc. Thesis Sharif University of Technology ; Rabiei, Hamid Reza (Supervisor)
Abstract
Monitoring large-scale networks is a critical yet challenging task. Enormous number of nodes and links, limited power, and lack of direct acceß to the entire network,are the most important difficulties. In applications such as network routing,where all nodes need to monitor the status of the entire network, the situation is even worse. In this thesis, a collaborative model in which nodes pick up information from measurements generated by other nodes, is proposed. Considering the fact that in most cases the networked data is sufficiently sparse, we used the Compreßive Sensing theory in the recovery phase of the proposed method. Using this model, for the first time, an upper bound is derived...
A Framework for Agile Supply Chain based on Industry 4.0 Enabling Technologies
, M.Sc. Thesis Sharif University of Technology ; Habibi, Moslem (Supervisor)
Abstract
Supply chain management aims to increase customer satisfaction and satisfy demand with the lowest cost by establishing coordination and cooperation among the chain members. However, considerable concerns along supply chain management are reported from both academicians and practitioners. Security, visibility, transparency and traceability are the main challenges confronting supply chain management. The emerging technology named Blockchain is able to address the mentioned challenges by integrating with supply chain management. A prominent point to consider is that whether it is absolutely necessary to adopt blockchain technology in a system or not. If yes, how blockchain should be implemented...
Experimental study on the shear strength of sandy clay infilled regular rough rock joints
, Article Rock Mechanics and Rock Engineering ; Volume 48, Issue 3 , May , 2015 , Pages 907-922 ; 07232632 (ISSN) ; Sadaghiani, M. H ; Sharif University of Technology
Springer Verlag Wien
2015
Abstract
Infill materials in rock joints usually cause a reduction in the joint shear strength. The shear behavior of rock discontinuities depends upon whether they are clean and unfilled or filled, so this concern invites accurate understanding of the shear behavior and strength of infilled joints. A series of constant normal load direct shear tests was performed to investigate the shear strength of artificial samples with infilled rough joint surfaces having different asperity and infill characteristics. The current study focuses on the effects of factors that influence the shear strength of infilled rock joints samples, with emphasis on forward and reverse shearing. In the forward cycle, the front...
Study on Effect of Regular Roughness and Filling of Discontinuity in Shear Strength of Rock Mass with Laboratory Tests
, Ph.D. Dissertation Sharif University of Technology ; Sedghiani, Mohammad Hossein (Supervisor)
Abstract
Effect of discontinuities on shear behavior and shear strength of rock masses are very important. Infill materials found in natural rock discontinuities may cause a reduction in joint shear strength, influencing rock mass stability. Many researches have been done in the field of behavior of infilled and unfilled discontinuities. The models and relationships developed through such studies will be of immense help to mining and civil engineering projects in rock masses. Rough surfaces in rock masses are found in rock joints. In general this research includes studies on the effect of joint surface mechanical and geometrical characteristics, asperity orientation and infill materials mechanical...
Analysis of the TESLA Authentication Protocol in VANET and its Impact on Safety
, M.Sc. Thesis Sharif University of Technology ; Jahangir, Amir Hossein (Supervisor)
Abstract
Security is an important issue in Vehicular Ad Hoc Networks (VANETs),which are mainly aimed at enhancing safety. Analysis of security mechanisms can help design and implement secure communication establishment methods in such networks. Formal verification is an analysis approach, with the purpose of proving the correctness of a system based on defined precise assumptions. Formal verification is applicable to a vast range of systems, such as time-critical reactive systems. Timed formal verification of cryptographic protocols is a subject that has gained a lot of attention in the recent two decades. The TESLA broadcast authentication protocol is on one hand an efficient, standardized method...
Analysis of TESLA protocol in vehicular ad hoc networks using timed colored Petri nets
, Article 2015 6th International Conference on Information and Communication Systems, ICICS 2015, 7 April 2015 through 9 April 2015 ; April , 2015 , Pages 222-227 ; 9781479973491 (ISBN) ; Amin, F ; Jahangir, A. H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Authentication is an essential security requirement in safety-related vehicle-to-vehicle applications in VANETs. TESLA is one of the most popular broadcast source authentication protocols proposed and standardized for this purpose. Having strict time constraints and being prone to GPS synchronization errors make the analysis of this protocol challenging. In this paper, we utilize a timed model checking approach based on timed colored Petri nets to model and verify TESLA considering its time-sensitive behaviors. In this way, we show how neglecting timing aspects in protocol design and in protocol modelling can lead to successfully launched attacks and erroneous analyses respectively, and how...
A 1.5V 150MS/s current-mode sample-and-hold circuit
, Article 2005 European Conference on Circuit Theory and Design, Cork, 28 August 2005 through 2 September 2005 ; Volume 2 , 2005 , Pages 91-94 ; 0780390660 (ISBN); 9780780390669 (ISBN) ; Rajaee, O ; Jahanian, A ; Bakhtiar, M. S ; Sharif University of Technology
2005
Abstract
A high-speed current-mode sample-and-hold circuit is presented. This circuit allows for high sampling speed together with high linearity and precision. The sample-and-hold circuit has been designed and simulated in standard 0.18μm CMOS technology with 1.5V supply voltage. It is capable of operation with sampling frequency of 150MHz (300MHz using double sampling technique) for 12-bit accuracy using 3.7mW power
Secondary particles spectra in the decay of a polarized top quark with anomalous tWb couplings
, Article Journal of Physics G: Nuclear and Particle Physics ; Volume 34, Issue 1 , 2007 ; 09543899 (ISSN) ; Sharif University of Technology
2007
Abstract
An analytic expression for energy and angular dependence of a secondary charged lepton in the decay of a polarized top quark with anomalous tWb couplings in the presence of all anomalous couplings are derived. The angular distribution of the b-quark is derived as well. It is presented that the charged lepton spin correlation coefficient is not very sensitive to the anomalous couplings. However, the b-quark spin correlation coefficient is sensitive to anomalous couplings and could be used as a powerful tool in the search for non-SM coupling. © 2007 IOP Publishing Ltd
Semileptonic decay of a polarized top quark in the noncommutative standard model
, Article Physical Review D - Particles, Fields, Gravitation and Cosmology ; Volume 74, Issue 2 , 2006 ; 15507998 (ISSN) ; Sharif University of Technology
2006
Abstract
In this paper we study the noncommutative effects to the lepton spectrum from the decay of a polarized top quark. It is shown that the lowest contribution comes from the quadratic terms of the noncommutative parameter. The deviations from the standard model are significant for small values of the noncommutative characteristic scale. However, the charged lepton spin correlation coefficient has a remarkable deviation from the standard model from very low values of the noncommutative characteristic scale to 1 TeV. © 2006 The American Physical Society
Model predictive control of blood sugar in patients with type-1 diabetes
, Article Optimal Control Applications and Methods ; Volume 37, Issue 4 , 2016 , Pages 559-573 ; 01432087 (ISSN) ; Shahrokhi, M ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
In this article, two adaptive model predictive controllers (AMPC) are applied to regulate the blood glucose in type 1 diabetic patients. The first controller is constructed based on a linear model, while the second one is designed by using a nonlinear Hammerstein model. The adaptive version of these control schemes is considered to make them more robust against model mismatches and external disturbances. The least squares method with forgetting factor is used to update the model parameters. For simulation study, two well-known mathematical models namely, Puckett and Hovorka which describe the dynamical behavior of patient's body have been selected. The performances and robustness of the...
Anomalous single top quark production at the LHC
, Article Physica Scripta ; Volume 82, Issue 3 , 2010 ; 00318949 (ISSN) ; Pooya, G ; Sharif University of Technology
2010
Abstract
The anomalous top quark interactions with gluon (tug, tcg) allow the production of single top quarks at the Large Hadron Collider (LHC). Using the angular distribution of the charged lepton from the W boson in the top decay, we show that with the data of 10 fb-1 of integrated luminosity and in the collisions with the center of mass energy of 14TeV, the anomalous up and charm quarks coupling parameters κu,c/Λ can be measured down to 0.005 and 0.007 TeV-1, respectively
Experimental and analytical study of telescopic lead yielding damper
, Article Journal of Constructional Steel Research ; Volume 150 , 2018 , Pages 371-383 ; 0143974X (ISSN) ; Pournamazian Najafabadi, E ; Sharif University of Technology
2018
Abstract
In this study, a novel type of passive energy dissipation device called a Telescopic Lead Yielding Damper (TLYD) is proposed and analyzed. This device comprises co-axial steel cylinders and lead rings, such that these rings act as shear locks between the steel cylinders. TLYDs dissipate energy through the plastic shear deformation of lead metal. The telescopic mechanism used in TLYDs allows these small-sized dampers to tolerate large axial displacements with low fatigue. For each telescopic level, a yield plateau is added to the hysteresis behavior of TLYD devices. Each yield plateau resists a different performance level, namely design-based and maximum credible earthquakes. Seven...
Wireless electrochemical preparation of gradient nanoclusters consisting of copper(II), stearic acid and montmorillonite on a copper wire for headspace in-tube microextraction of chlorobenzenes
, Article Microchimica Acta ; Volume 185, Issue 1 , 2018 ; 00263672 (ISSN) ; Bagheri, H ; Sharif University of Technology
Springer-Verlag Wien
2018
Abstract
This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy,...
Numerical study of bacteria removal from microalgae solution using an asymmetric contraction-expansion microfluidic device: a parametric analysis approach
, Article Heliyon ; Volume 9, Issue 10 , 2023 ; 24058440 (ISSN) ; Sattari Najafabadi, M ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
Microalgae have been remarkably taken into account due to their wide applications in the biopharmaceutical, nutraceutical and bio-energy fields. However, contamination of microalgae with bacteria still appears to be a concern, adversely impacting products’ quality and process efficiency. Microalgae decontamination with conventional techniques is usually expensive and time-consuming. Moreover, damage to microalgae cells is highly possible. Asymmetric contraction-expansion microchannels (Asym-CEMCs) are promising passive microfluidic devices that can overcome conventional techniques' drawbacks with their standing-out features. However, the flexibility of Asym-CEMCs performance arising from...
Modeling of retention behaviors of most frequent components of essential oils in polar and non-polar stationary phases
, Article Journal of Separation Science ; Volume 34, Issue 13 , 2011 , Pages 1538-1546 ; 16159306 (ISSN) ; Ebrahimi Najafabadi, H ; Sharif University of Technology
2011
Abstract
The gas chromatography retention indices of 100 different components of essential oils, on three columns with stationary phases of different polarities, were used to develop robust quantitative structure-retention relationship (QSRR) models. Two linear models with only one variable, i.e. solvation entropy, were developed, which explain 95 and 94% of variances of the test set for dimethyl silicone and dimethyl silicone with 5% phenyl group columns, respectively. These models are extremely simple and easy to interpret, but they show higher errors compared with more robust models such as partial least square (PLS) and ridge regressions. For the third column (polyethylene glycol (PEG)), 24...
The use of ladder particle swarm optimisation for quantitative structure-activity relationship analysis of human immunodeficiency virus-1 integrase inhibitors
, Article Molecular Simulation ; Volume 37, Issue 15 , 2011 , Pages 1221-1233 ; 08927022 (ISSN) ; Ebrahimi-Najafabadi, H ; Sharif University of Technology
2011
Abstract
This contribution focuses on the use of ladder particle swarm optimisation (LPSO) on modelling of oxadiazole- and triazolesubstituted naphthyridines as human immunodeficiency virus-1 integrase inhibitors. Artificial neural network (ANN) and Monte Carlo cross-validation techniques were combined with LPSO to develop a quantitative structure-activity relationship model. The techniques of LPSO, ANN and sample set partitioning based on joint x-y distances were applied as feature selection, mapping and model evaluation, respectively. The variables selected by LPSO were used as inputs of Bayesian regularisation ANN. The statistical parameters of correlation of deterministic, R2, and...
Mathematical performance modelling of adaptive wormhole routing in optoelectronic hypercubes
, Article Journal of Parallel and Distributed Computing ; Volume 67, Issue 9 , Volume 67, Issue 9 , 2007 , Pages 967-980 ; 07437315 (ISSN) ; Sarbazi Azad, H ; Sharif University of Technology
2007
Abstract
In this paper, an analytical performance model for adaptive wormhole routing in the hypercube-based optical transpose interconnection system (OTIS-hypercube) is proposed and validated. Using this model, the performance merits of the OTIS-hypercube are discussed. We also compare the performance of the OTIS-hypercube with that of equivalent hypercube network under different implementation constraints. Compared to pure simulation results, the presented model can serve as a more appropriate and compact method to display the performance characteristics of OTIS-hypercube networks. © 2007 Elsevier Inc. All rights reserved
Fast Centralized Model Predictive Control of Signal Splitting in Large Scale Urban Road Networks
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
With the rapid increase in the number of vehicles and the limitations on the extension of transportation network infrastructure, the need for utilizing proper methods to reduce traffic congestion has become increasingly important. One way to reduce traffic congestion is to control the signal splitting of traffic lights. Model predictive control (MPC) has been utilized so far by using different models of traffic flow dynamics in this field. Due to the high computational effort of MPC at each step time, the real-time implementation for large-scale networks has become a big challenge. Store-And-forward (SAF) is one of the traffic flow models that, due to its simplicity, makes it possible to...