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Implicit effect of decoding time on fault tolerance in erasure coded cloud storage systems
, Article 20th International Computer Science and Engineering Conference: Smart Ubiquitos Computing and Knowledge, ICSEC 2016, 14 December 2016 through 17 December 2016 ; 2017 ; 9781509044207 (ISBN) ; Miremadi, S. G ; Alinezhad Chamazcoti, S ; Sharif University of Technology
2017
Abstract
International Data Company (IDC) has estimated the total amount of digital data stored in the world will reach 40 thousand Exabytes at the end of 2020. The idea of accessing this volume of data, anywhere at any time by exploiting commodity hardware, led to the introduction of cloud storage. The abounded rate and variety of failures in the equipment used in cloud storage systems, placed fault tolerance, at top of the challenges in these systems. Hadoop Distributed File System (HDFS) has provided cloud with reliable storage via replication. Storage overhead of replication is high and therefore it's going to be replaced with erasure codes. Despite the significant number of researches on...
Improving the performance of lithium-sulfur batteries using sulfur-(TiO2/SiO2) yolk-shell nanostructure
, Article Journal of Nanostructures ; Volume 10, Issue 1 , 2020 , Pages 76-82 ; Sepahvand, S ; Hossieni, F ; Ghasemi, S ; Sanaee, Z ; Sharif University of Technology
University of Kashan
2020
Abstract
Lithium-Sulfur (Li-S) batteries are considered as one of the promising candidates for next-generation Li batteries in near future. Although, these batteries are suffering from certain drawbacks such as rapid capacity fading during the charge and discharge process due to the dissolution of polysulfides. In this paper, Sulfur/metal oxide (TiO2 and SiO2) yolk-shell structures have been successfully synthesized and utilized to overcome this problem and improve the electrochemical performance of sulfur cahtode material. Prepared materials have been characterized using Scanning Electron Microscopy(SEM), Transmission Electron Microscopy(TEM) and X-ray diffraction (XRD) techniques. The results show...
Weighing criteria and prioritizing strategies to reduce motorcycle-related injuries using combination of fuzzy topsis and ahp methods
, Article Advances in Transportation Studies ; Volume 54 , 2021 , Pages 217-234 ; 18245463 (ISSN) ; Safaei, N ; Masoud, A ; Seyedekrami, S ; Sharif University of Technology
Aracne Editrice
2021
Abstract
Unsafe driving behavior and hazardous environmental conditions lead lo traffic crashes and injuries. The annual rale of road crashes in Iran is twenty times higher than the world's average. Motorcycle crashes have higher fatality rates than other motor vehicle crashes, and they exert psychological pressure on the communities and have adverse economic consequences for the societies. This paper analyzes Tehran's motorcycle crash data and investigates the effective underlying factors. Seven strategies were presented and prioritized to reduce the number and severity of motorcycle crashes. The fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) combined with the...
Multiobjective design of an S control chart for monitoring process variability
, Article International Journal of Multicriteria Decision Making ; Volume 2, Issue 4 , 2012 , Pages 408-424 ; 2040106X (ISSN) ; Kazemzadeh, R. B ; Niaki, S. T. A ; Sharif University of Technology
2012
Abstract
Optimally determining parameters of the control chart is a critical task for control chart designer to improve the processes. However, difficulty in an accurate estimation of various cost and process parameters is one of the barriers while someone desire to determine these parameters by means of economic approach. In order to reduce cost penalties for not knowing the true values of the parameters and to study the impact of further improvement in detection power of the chart on the economic performance of the S control chart, this paper aims to develop a multiobjective model of the economic-statistical design of the S control chart to minimise the mean hourly loss cost as well as minimising...
Multi-Objective economic statistical design of X-Bar control chart considering taguchi loss function
, Article International Journal of Advanced Manufacturing Technology ; Volume 59, Issue 9-12 , April , 2012 , Pages 1091-1101 ; 02683768 (ISSN) ; Kazemzadeh, R. B ; Niaki, S. T. A ; Sharif University of Technology
2012
Abstract
Shewhart charts are the most popular control charts that can be used to monitor variable quality characteristics in a production process. In this paper, a multi-objective model of the economic statistical design of the X-bar control chart is first proposed by incorporating the Taguchi loss function and the intangible external costs. The model minimizes the mean hourly loss cost while minimizing out-of-control average run length and maintaining reasonable in-control average run length. A multiobjective evolutionary algorithm, namely NSGA-II, is then developed and used to obtain the Pareto optimal solution of the model. Some sensitivity analyses are next performed to investigate the effect of...
Dynamic routing of data stream tuples among parallel query plan running on multi-core processors
, Article Distributed and Parallel Databases ; Volume 30, Issue 2 , April , 2012 , Pages 145-176 ; 09268782 (ISSN) ; Sharifrazavian, A ; Sharifi, M ; Haghjoo, M. S ; Sharif University of Technology
2012
Abstract
In this paper, a method for fast processing of data stream tuples in parallel execution of continuous queries over a multiprocessing environment is proposed. A copy of the query plan is assigned to each of processing units in the multiprocessing environment. Dynamic and continuous routing of input data stream tuples among the graph constructed by these copies (called the QueryMega Graph) for each input tuple determines that, after getting processed by each processing unit (e.g., processor), to which next processor it should be forwarded. Selection of the proper next processor is performed such that the destination processor imposes the minimum tuple latency to the corresponding tuple, among...
Synthesis and characterization of carbon-stabilized magnesium nanoparticles
, Article Journal of Cluster Science ; 2016 , Pages 1-9 ; 10407278 (ISSN) ; Asgari, F ; Arzi, M ; Hojaji, A ; Sadrnezhaad, S. K ; Sharif University of Technology
Springer New York LLC
2016
Abstract
Magnesium nanopowder has attracted many interests in the recent years, which has a very difficult and costly synthesis process because of its high activity. In this work, magnesium nanoparticles stabilized with amorphous carbon (Mg–C nanoparticles) were synthesized by submerged arc discharge technique in kerosene. The arc discharge was generated between two electrodes of magnesium at the arc current of 1 A and arc voltage of 50 V. Mg–C nanoparticles were characterized by various techniques. Dynamic light scattering result indicated that size of magnesium nanoparticles is about 35 nm. X-ray diffraction showed that the produced sample consisted of hexagonal magnesium and amorphous carbon and...
Synthesis and characterization of carbon-stabilized magnesium nanoparticles
, Article Journal of Cluster Science ; Volume 28, Issue 3 , 2017 , Pages 881-889 ; 10407278 (ISSN) ; Asgari, F ; Arzi, M ; Hojaji, A ; Sadrnezhaad, S. K ; Sharif University of Technology
Springer New York LLC
2017
Abstract
Magnesium nanopowder has attracted many interests in the recent years, which has a very difficult and costly synthesis process because of its high activity. In this work, magnesium nanoparticles stabilized with amorphous carbon (Mg–C nanoparticles) were synthesized by submerged arc discharge technique in kerosene. The arc discharge was generated between two electrodes of magnesium at the arc current of 1 A and arc voltage of 50 V. Mg–C nanoparticles were characterized by various techniques. Dynamic light scattering result indicated that size of magnesium nanoparticles is about 35 nm. X-ray diffraction showed that the produced sample consisted of hexagonal magnesium and amorphous carbon and...
Novel hot milling approach for the synthesis of fine PbZr0.95Ti0.05O3 powders
, Article Ceramics International ; Volume 45, Issue 18 , 2019 , Pages 24176-24181 ; 02728842 (ISSN) ; Hojaji Najafabadi, A. R ; Safaei, S ; Sadrnezhaad, Kh ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A new and effective hot milling system was designed and applied to the synthesis of PbZr0.95Ti0.05O3 (PZT) powder. PbO, ZrO2 and TiO2 powders were used as starting materials and hot milled at various temperatures ranging from 10 ̊°C to 800 ̊°C. The obtained powders were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Results indicated that pure, crystalline, and fine PZT powders with the average particle size of 170 nm can be successfully synthesized directly after a relatively short synthesis time of 12 h at lower temperature of 800 ̊°C by the hot milling technique. In contrast to this method, this study demonstrates that conventional solid-state...
Observer-free control of satellite attitude using a single vector measurement
, Article IEEE Transactions on Aerospace and Electronic Systems ; Vol. 50, issue. 3 , 2014 , pp. 2070-2081 ; ISSN: 00189251 ; Namvar, M ; Sharif University of Technology
2014
Abstract
The existing methods in attitude control of satellites are based on using the estimate of satellite attitude, which is usually generated by using multiple vector measurements. In this paper we propose an output feedback controller that directly uses a single vector measurement and does not use an attitude estimator. The output feedback gain is computed by solving a generalized Riccati differential equation (GRDE). The existence of a solution to the GRDE depends on a uniform controllability condition
Output feedback control of satellite attitude using a single vector measurement
, Article Proceedings of the IEEE Conference on Decision and Control, 10 December 2012 through 13 December 2012, Maui, HI ; 2012 , Pages 490-495 ; 01912216 (ISSN) ; Namvar, M ; Sharif University of Technology
2012
Abstract
The existing methods in attitude control of satellites are based on employing the estimate of satellite attitude which is usually generated by using multiple vector measurements. In this paper we propose an output feedback control law that directly uses a single vector measurement and gyro, and without any need for estimating the satellite attitude. The output feedback gain is computed by solving a generalized Riccati time varying differential equation. We assume the moment-of-inertia matrix of satellite is unknown. The controller guarantees asymptotic convergence of the attitude to its desired value. A realistic simulation is presented where a magnetometer is used to provide the single...
3D motion recognition using HMM and nearest neighbor method
, Article Proceedings of the IASTED International Conference on Signal Processing, Pattern Recognition and Applications, SPPRA 2012 ; 2012 , Pages 17-22 ; 9780889869219 (ISBN) ; Jahed, M ; Sharif University of Technology
ACTA Press
2012
Abstract
Gesture and motion recognition are needed for a variety of applications. The use of human hand motions as a natural interface tool has motivated researchers to conduct research in the modeling, analysis and recognition of various hand movements. In this work, we introduce a 3-D hand motion recognition. We use 3-D landmarked points on finger tips and joints followed by a HMM (Hidden Markov Model) to recognize hand motions. Experimentally, in an effort to evaluate the formation of hand gestures similar to those used in rehabilitation sessions, we studied three hand motions. Using natural hand motion features in an uncontrolled environment, we were able to classify, differentiate and quantify...
On the design of graphene oxide nanosheets membranes for water desalination
, Article Desalination ; Volume 422 , 2017 , Pages 83-90 ; 00119164 (ISSN) ; Tavakoli, R ; Sharif University of Technology
Elsevier B.V
2017
Abstract
According to current researches, graphene oxide (GO) membranes show promising desalination properties due to ease of synthesis, low production cost, and high efficiency. There are several experimental works to study ionic sieving properties of GO membranes. However, it is difficult to characterize atomistic mechanism of water permeation and ion rejection by experimental approaches. On the other hand, there exist a few reports in which the atomistic picture of water permeation across GO membranes is investigated by means of molecular dynamics (MD) simulation. In the present work, in addition to water desalination, the atomic scale mechanism of ion rejection is studied using large scale MD...
Quine-McCluskey classification
, Article 2007 IEEE/ACS International Conference on Computer Systems and Applications, AICCSA 2007, Amman, 13 May 2007 through 16 May 2007 ; 2007 , Pages 404-411 ; 1424410312 (ISBN); 9781424410316 (ISBN) ; Beigy, H ; Sharif University of Technology
2007
Abstract
In this paper the Karnaugh and Quine-McCluskey methods are used for symbolic classification problem, and then these methods are compared with other famous available methods. Because the data in classification problem is very large, some changes should be applied in the original Quine-McCluskey (QMC) algorithm. We proposed a new algorithm that applies the QMC algorithm greedily calling it GQMC. It is surprising that GQMC results are most of the time equal to QMC. GQMC is still very slow classifier and it can be used when the number of attributes of the data is small, and the ratio of training data to the all possible data is high. © 2007 IEEE
Entanglement Spectrum of One Dimensional Ising Model in Transverse Field
, M.Sc. Thesis Sharif University of Technology ; Langari, Abdollah (Supervisor)
Abstract
Entanglement spectrum is the set of eigenvalues of reduced density matrix for a definite state. It contains more information than the entanglement entropy. This spectrum can show entanglement measure, quantum phase transition and topological order in a system. In recent years, the entanglement spectrum for several models has been studied. The entanglement spectrum shows a correspondence to the energy spectrum within some specific regions, which are related to the edge state of the system; It has been verified for the Heisenberg ladder [1] and fractional quantum Hall effect [3]. Moreover, the topological order can be seen in the entanglement spectrum. There exists an acceptable adaption...
Automatic Hand and Wrist Motion Tracking and Assessment Using Stereo Vision and Video Processing
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Gesture and motion evaluation are needed for a variety of applications. The use of human hand motions as a natural interface tool has motivated researchers to conduct research in the modeling, analysis and evaluation of various hand movements. In particular, human-computer intelligent interaction has been a focus of research in vision-based gesture recognition. In this work, we introduce a 3-D hand model evaluation method that offers flexible and elaborate representation of hand motion. We used landmarked points on tips and joints of the fingers and calculated the 3-D coordinates of these points through a stereo vision system followed by an HMM (Hidden Markov Model) to recognize hand...
Fault Tolerance in Cloud Storage Systems Using Erasure Codes
, M.Sc. Thesis Sharif University of Technology ; Miremadi, Ghassem (Supervisor)
Abstract
International Data Company (IDC) has reported, at the end of 2020, the total amount of digital data stored in the entire world will reach 40 thousand Exabytes. The idea of accessing this volume of data, anywhere at any time by exploiting commodity hardware, led into the introduction of cloud storage. The abounded rate and variety of failures in the equipment used in cloud storage systems, placed fault tolerance, at top of the challenges in these systems. HDFS layer in Hadoop has provided cloud with reliable storage. Replication is the conventional method to protect data against failures in HDFS. But the storage overhead is a big deal and therefore designers are tending towards erasure codes....
Attitude Control of Satellite Using a Single Vector Measurement and Gyro
, Ph.D. Dissertation Sharif University of Technology ; Namvar, Mehrzad (Supervisor)Energy-Aware Routing in Internet of Things
, Ph.D. Dissertation Sharif University of Technology ; Ejlali, Alireza (Supervisor)
Abstract
Internet of Things (IoT) is a communicative infrastructure, which establishes IP-based connections between many smart devices with limited energy supplies. The gathering of such an enormous number of connected devices would impose many challenges, with routing the most important issue. Standardization of the IPv6 Routing Protocol for Low-power and Lossy Networks (RPL) was a major step towards fulfilling the IoT routing requirements. The key element in determining the routing policies and creation of the topology in RPL is the objective function. According to our studies, more than 97% of the consumed energy of a node in wireless networks is due to transceiver activities. On the other hand,...
Preparation and characterization of poly-lactic acid based films containing propolis ethanolic extract to be used in dry meat sausage packaging
, Article Journal of Food Science and Technology ; Volume 57, Issue 4 , 2020 , Pages 1242-1250 ; Roosta Azad, R ; Sharif University of Technology
Springer
2020
Abstract
In this study, active poly lactic acid (PLA) films containing 0, 10, 20 and 40% w/w propolis extract (PE), as active agent, were developed. A high amount of phenolic content (PC) was measured in PE. The antioxidant effect of active PLA films was determined by measuring the PC of sausage slices after 0, 2 and 4 days storage at refrigerator. Results showed that phenolic compounds of PE were released from PLA films in quantities proportional to PE concentration. Disc diffusion test indicated that PE showed an inhibitory effect against Staphylococcus aureus and Pseudomonas aeruginosa bacterial species but was more effective against gram-positive species. PE containing PLA films had antimicrobial...