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ebrahimpour--reza
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, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Akbari, Javad (Supervisor)
Abstract
In Ultrasonic Assisted Machining (UAM) a mechanical vibration is added to the relative motion of the tool and workpiece. The frequency of vibration is typically from 20kHz to 100kHz and the amplitude is in the range of 10 to 20 microns. Experiments show that using this method improves the machining performance. Reduction in machining forces and tool wear and improving the cooling condition are some of the advantages of UAM. In this work, the forces of ultrasonic assisted milling are investigated. Applying thin shear plane theorem provides an acceptable theoretical base with minimum dependence on experimental data to analyze machining forces. To evaluate the model and find the effect of...
Experimental evaluation of the effect of boulders and fines in biodegradable organic materials on the improvement of solar stills
, Article Solar Energy ; Volume 247 , 2022 , Pages 453-467 ; 0038092X (ISSN) ; Behshad Shafii, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this research, for the first time, the effect of primary particles (boulders) and secondary particles (fines) in organic mixtures of coffee, black walnut hull, madder, and tea (which are cheap, abundant, and biodegradable) on the improvement of solar stills' daily efficiency is evaluated as an alternative to metal-based nanofluids. A laboratory still simulator is utilised under laboratory conditions to measure the organic mixture's behaviour accurately. Furthermore, the effect of the concentration of organic mixtures and the particle size of organic materials are investigated, as well as the effect of boulders and fines, independently. In addition, two identical solar still systems are...
A new framework for small sample size face recognition based on weighted multiple decision templates
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 22 November 2010 through 25 November 2010, Sydney, NSW ; Volume 6443 LNCS, Issue PART 1 , November , 2010 , Pages 470-477 ; 03029743 (ISSN) ; 3642175368 (ISBN) ; Masoudnia, S ; Ebrahimpour, R ; Sharif University of Technology
2010
Abstract
In this paper a holistic method and a local method based on decision template ensemble are investigated. In addition by combining both methods, a new hybrid method for boosting the performance of the system is proposed and evaluated with respect to robustness against small sample size problem in face recognition. Inadequate and substantial variations in the available training samples are the two challenging obstacles in classification of an unknown face image. At first in this novel multi learner framework, a decision template is designed for the global face and a set of decision templates is constructed for each local part of the face as a complement to the previous part. The prominent...
Design, Manufacture, and Investigation of the Desalination System Using Direct Absorption Solar Collector with Organic Colloids and External Condenser
, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor)
Abstract
The use of nanofluids for direct absorption of solar irradiance to produce freshwater has received much attention. Water-based nanofluids include metals, metal oxides, and nanocarbon-based fluids, which increase collector efficiency. On the other hand, the production cost of nanofluids is high, and when discharging the brine after the desalination process, these nanofluids cause environmental issues. Therefore, water-based organic colloids of coffee, walnut shell, black tea, and madder have been studied to overcome these problems. To accurately measure the behavior of colloids, laboratory single slope solar still was used in laboratory conditions. Also, two single slope solar stills with the...
Experimental evaluation of a solar-driven adsorption desalination system using solid adsorbent of silica gel and hydrogel
, Article Environmental Science and Pollution Research ; Volume 29, Issue 47 , 2022 , Pages 71217-71231 ; 09441344 (ISSN) ; Behshad Shafii, M ; Ebrahimpour, B ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Nowadays, the world is facing a shortage of fresh water. Utilizing adsorbent materials to adsorb air moisture is a suitable method for producing freshwater, especially combining the adsorption desalination system with solar energy devices such as solar collectors. The low temperature of solar collectors has caused some water to remain in the adsorbents in the desorption process and has reduced the possibility of using these systems. In this research, for the first time, an evacuated tube collector (ETC) is used as an adsorbent bed so that the temperature of the desorption process reaches higher values and as a result, more fresh water is expected to produced. In this study, two adsorption...
Modeling and techno-economic study of a solar reverse osmosis desalination plant
, Article International Journal of Environmental Science and Technology ; Volume 19, Issue 9 , 2022 , Pages 8727-8742 ; 17351472 (ISSN) ; Hajialigol, P ; Boroushaki, M ; Shafii, M. B ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
In this research, the design of a solar reverse osmosis desalination plant was investigated by integrating various components using TRNSYS and ROSA software. To this goal, a two-stage reverse osmosis system with 50% recovery in the city of Chabahar was modeled. The calculations were performed in three different case studies, i.e., a photovoltaic power plant, a solar collector power plant with Organic Rankine Cycles, and a photovoltaic thermal power plant with Organic Rankine Cycles, with the reverse osmosis desalination plant being a novel investigation. Water production and electrical energy generation of each case study were evaluated both on a daily and yearly bases. The simulation...
A trainable neural network ensemble for ECG beat classification
, Article World Academy of Science, Engineering and Technology ; Volume 70 , 2010 , Pages 788-794 ; 2010376X (ISSN) ; Zakernejad, S ; Faridi, S ; Javadi, M ; Ebrahimpour, R ; Sharif University of Technology
2010
Abstract
This paper illustrates the use of a combined neural network model for classification of electrocardiogram (ECG) beats. We present a trainable neural network ensemble approach to develop customized electrocardiogram beat classifier in an effort to further improve the performance of ECG processing and to offer individualized health care. We process a three stage technique for detection of premature ventricular contraction (PVC) from normal beats and other heart diseases. This method includes a denoising, a feature extraction and a classification. At first we investigate the application of stationary wavelet transform (SWT) for noise reduction of the electrocardiogram (ECG) signals. Then...
Evidence-based mixture of MLP-experts
, Article Proceedings of the International Joint Conference on Neural Networks, 18 July 2010 through 23 July 2010 ; July , 2010 ; 9781424469178 (ISBN) ; Rostami, M ; Tabassian, M ; Sajedin, A ; Ebrahimpour, R ; Sharif University of Technology
2010
Abstract
Mixture of Experts (ME) is a modular neural network architecture for supervised learning. In this paper, we propose an evidence-based ME to deal with the classification problem. In the basic form of ME the problem space is automatically divided into several subspaces for the experts and the outputs of experts are combined by a gating network. Satisfactory performance of the basic ME depends on the diversity among experts. In conventional ME, different initialization of experts and supervision of the gating network during the learning procedure, provide the diversity. The main idea of our proposed method is to employ the Dempster-Shafer (D-S) theory of evidence to improve determination of...
Mixture of mlp-experts for trend forecasting of time series: A case study of the tehran stock exchange
, Article International Journal of Forecasting ; Volume 27, Issue 3 , 2011 , Pages 804-816 ; 01692070 (ISSN) ; Nikoo, H ; Masoudnia, S ; Yousefi, M. R ; Ghaemi, M. S ; Sharif University of Technology
2011
Abstract
A new method for forecasting the trend of time series, based on mixture of MLP experts, is presented. In this paper, three neural network combining methods and an Adaptive Network-Based Fuzzy Inference System (ANFIS) are applied to trend forecasting in the Tehran stock exchange. There are two experiments in this study. In experiment I, the time series data are the Kharg petrochemical company's daily closing prices on the Tehran stock exchange. In this case study, which considers different schemes for forecasting the trend of the time series, the recognition rates are 75.97%, 77.13% and 81.64% for stacked generalization, modified stacked generalization and ANFIS, respectively. Using the...
GTED: Graph traversal edit distance
, Article 22nd International Conference on Research in Computational Molecular Biology, RECOMB 2018, 21 April 2018 through 24 April 2018 ; Volume 10812 LNBI , 2018 , Pages 37-53 ; 03029743 (ISSN); 9783319899282 (ISBN) ; Shrestha, A ; Sharifi Zarchi, A ; Gallagher, S. R ; Sahinalp, S. C ; Chitsaz, H ; Sharif University of Technology
Springer Verlag
2018
Abstract
Many problems in applied machine learning deal with graphs (also called networks), including social networks, security, web data mining, protein function prediction, and genome informatics. The kernel paradigm beautifully decouples the learning algorithm from the underlying geometric space, which renders graph kernels important for the aforementioned applications. In this paper, we give a new graph kernel which we call graph traversal edit distance (GTED). We introduce the GTED problem and give the first polynomial time algorithm for it. Informally, the graph traversal edit distance is the minimum edit distance between two strings formed by the edge labels of respective Eulerian traversals...
Graph traversal edit distance and extensions
, Article Journal of Computational Biology ; Volume 27, Issue 3 , 2020 , Pages 317-329 ; Shrestha, A ; Sharifi Zarchi, A ; Gallagher, S. R ; Sahinalp, S. C ; Chitsaz, H ; Sharif University of Technology
Mary Ann Liebert Inc
2020
Abstract
Many problems in applied machine learning deal with graphs (also called networks), including social networks, security, web data mining, protein function prediction, and genome informatics. The kernel paradigm beautifully decouples the learning algorithm from the underlying geometric space, which renders graph kernels important for the aforementioned applications. In this article, we give a new graph kernel, which we call graph traversal edit distance (GTED). We introduce the GTED problem and give the first polynomial time algorithm for it. Informally, the GTED is the minimum edit distance between two strings formed by the edge labels of respective Eulerian traversals of the two graphs....
PyGTED: Python application for computing graph traversal edit distance
, Article Journal of Computational Biology ; Volume 27, Issue 3 , 2020 , Pages 436-439 ; Shrestha, A ; Sharifi Zarchi, A ; Gallagher, S. R ; Sahinalp, S. C ; Chitsaz, H ; Sharif University of Technology
Mary Ann Liebert Inc
2020
Abstract
Graph Traversal Edit Distance (GTED) is a measure of distance (or dissimilarity) between two graphs introduced. This measure is based on the minimum edit distance between two strings formed by the edge labels of respective Eulerian traversals of the two graphs. GTED was motivated by and provides the first mathematical formalism for sequence coassembly and de novo variation detection in bioinformatics. Many problems in applied machine learning deal with graphs (also called networks), including social networks, security, web data mining, protein function prediction, and genome informatics. The kernel paradigm beautifully decouples the learning algorithm from the underlying geometric space,...
A misbehavior‐tolerant multipath routing protocol for wireless Ad hoc networks [electronic resource]
, Article International Journal of Research in Wireless Systems (IJRWS) ; Vol. 2, Issue 9, pp. , Sep. 2013 ; Pakravan, Mohammad Reza ; Aref, Mohammad Reza ; Sharif University of Technology
Abstract
Secure routing is a major key to service maintenance in ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. As a result of the resource limitations in such networks nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a novel data redirection method to mitigate the impact of node misbehavior on network...
Analysis and data-based reconstruction of complex nonlinear dynamical systems : using the methods of stochastic processes
, Book
Springer International Publishing
2019
Abstract
This book focuses on a central question in the field of complex systems: Given a fluctuating (in time or space), uni- or multi-variant sequentially measured set of experimental data (even noisy data), how should one analyse non-parametrically the data, assess underlying trends, uncover characteristics of the fluctuations (including diffusion and jump contributions), and construct a stochastic evolution equation?
Here, the term "non-parametrically" exemplifies that all the functions and parameters of the constructed stochastic evolution equation can be determined directly from the measured data.
The book provides an overview of methods that have been developed for the analysis of...
Here, the term "non-parametrically" exemplifies that all the functions and parameters of the constructed stochastic evolution equation can be determined directly from the measured data.
The book provides an overview of methods that have been developed for the analysis of...
Fabrication and Study of Mechanical Behavior of in Situ Microfibrillar- Reinforced Composites of Polypropylene/Recycled Poly (Ethylene Terephthalate)Toughened with Rubber Particles
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Alizadeh, Reza (Supervisor)
Abstract
The use of polymers is increasing day by day due to low density, reasonable price and ability to produce different products. On the other hand, the accumulation of polymer wastes in nature is one of the environmental concerns in today's world, which is mainly due to the widespread use of polymers in the packaging industry and disposable applications. In order to solve this problem, recycling is recommended as the most appropriate and economical solution. Because in addition to consuming polymer waste, it also saves energy and reduces carbon footprint.Polyethylene terephthalate (PET) is one of the polymeric materials which; It has a special place in the packaging industry and is widely used...
Characterization of Mechanical Properties of Polymer Nanocomposites with Spherical Inhomogeneities
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Bagheri, Reza (Supervisor)
Abstract
The improved properties of nanocomposites are not achievable with conventional composites. Scale effect is one the most important parameters in the physical and mechanical properties of polymeric nanocomposites. One of the physical phenomena, which can be related to the scale effect, is the very large interface between the nanoparticles and the polymeric matrices. Motional behavior and conformation of polymeric chains change near the nanoparticles surfaces. Due to high interface of the nanoparticles with the polymeric matrices the amount of these types of changes in the polymeric chains are so large that can change the physical and mechanical properties of polymeric nanocomposites. In this...
Solving High-Dimensional Differential Equations Using Machine Learning
, M.Sc. Thesis Sharif University of Technology ; Razvan, Mohammad Reza (Supervisor) ; Moghadasi, Reza (Co-Supervisor)
Abstract
The numerical solution of differential equations in high dimensions has always been a challenge and has been associated with various computational difficulties. These equations appear naturally in a variety of problems such as financial mathematics, control, and physics, and their optimal solution with high accuracy and speed can open new windows on new applications. Conventional methods such as Finite element and finite difference method in high dimensions lose their efficiency, which is a barrier to fast and accurate calculation of these equations. In this dissertation first, we review some theoretical and practical aspects of deep neural networks and then we try to examine the recent...
An Experimental Study of the Effects of Sweep Wing on the Boundary Layer of 2D Wing
, M.Sc. Thesis Sharif University of Technology ; Soltani, Mohammad Reza (Supervisor) ; Davari, Ali Reza (Co-Advisor)
Abstract
The behavior of boundary layer under the effect of the sweep angle is considered. The measurements were performed by a pitot tube rake. Three models with various sweep angels at angles of attack -2, 0 and 2 degree were tested. Both tip and root of all wings were closed by flat plates in order to prevent the flow to roll-up. However the flow field on the wing was still three-dimensional because of the sweep angle. The velocity on the wing has two components; longitudinal and lateral. The cross flow emerges due to the non-equilibrium of pressure and centrifugal forces. The velocity profiles showed that the magnitude of cross flow was stronger near the leading edge of the wing. The cross flow...
Synthesis of Antibiotic-eluting Chitosan-based Composite Coating by Electrophoretic Deposition for Bone Implants
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdol Reza (Supervisor) ; Bagheri, Reza (Supervisor)
Abstract
Drug-eluting bone implant coatings is a new era that has gained a lot of attention in recent years. In this matter, drug is loaded in the coating and local and targeted release of the drug results in preventing the side effects of implantation and increasing the healing process of the patient. The aim of this project was to synthesis the antibiotic eluting chitosan-based composite using electrophoretic deposition for bone implant coating. By using electrophoretic deposition chitosan and chitosan-bioglass composite coatings were synthesized. Then the probability of loading of drug into coating by using electrophoretic deposition was evaluated and by using this process chitosan and...
On small uniquely vertex-colourable graphs and Xu's conjecture [electronic resource]
, Article Discrete Mathematics ; Volume 223, Issues 1–3, 28 August 2000, Pages 93–108 ; Naserasr, Reza ; Sharif University of Technology
Abstract
Consider the parameter Λ(G) = |E(G)| - |V(G)|(k - 1) + (k2) for a k-chromatic graph G, on the set of vertices V(G) and with the set of edges E(G). It is known that Λ(G)≥0 for any k-chromatic uniquely vertex-colourable graph G (k-UCG), and, S.J. Xu has conjectured that for any k-UCG, G, Λ(G) = 0 implies that cl(G) = k; in which cl(G) is the clique number of G. In this paper, first, we introduce the concept of the core of a k-UCG as an induced subgraph without any colour-class of size one, and without any vertex of degree k - 1. Considering (k, n)-cores as k-UCGs on n vertices, we show that edge-minimal (k, 2k)-cores do not exist when k ≥ 3, which shows that for any edge-minimal k-UCG on 2k...