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hashemifar--alireza
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Oppositely charged MXene fibers as a highly efficient osmotic power generator from sea and river water
, Article Journal of Materials Chemistry A ; Volume 10, Issue 46 , 2022 , Pages 24915-24926 ; 20507488 (ISSN) ; Esfandiar, A ; Sharif University of Technology
Royal Society of Chemistry
2022
Abstract
Ion-exchange membrane-based reverse electrodialysis (RED) shows great potential for harvesting osmotic energy from seawater and converting it to electricity. However, their low energy conversion efficiency and huge ionic resistance hinder their application on large scales. The implementation of nanofluidic channels in RED devices can significantly improve the performance of osmotic power generators due to their selective and fast ion transport. However, technical challenges in scalable processing at the nanoscale and ion-selective membranes restrict their development in economically viable generators. Here, we report fibrous-based channels as positively and negatively charged MXene fibers...
Study of Ion Transport from the Two-Dimensional Structure of MXene
, M.Sc. Thesis Sharif University of Technology ; Esfandiar, Ali (Supervisor)
Abstract
Reverse electrodialysis-based membranes are one of the most promising approaches to osmotic energy production. However, conventional reverse electrodialysis membranes have high strength and insufficient mass transfer, which leads to low power density and efficiency. In recent decades, the transport of ions at the nanoscale for the manufacture of reverse electrodialysis machines has attracted much attention. Compared to conventional devices, power density and energy conversion efficiency increase dramatically due to space constraints and electrostatic interactions at the nanoscale. Lamellar nanostructures, which can be easily fabricated by stacking two-dimensional nanosheets, may be a...
An Analysis of a Mathematical Model Describing the Geographic Spread of Dengue Disease
, M.Sc. Thesis Sharif University of Technology ; Hesaraki, Mahmoud (Supervisor)
Abstract
We consider a system of nonlinear partial differential equations corresponding to a generalization of a mathematical model for geographical spreading of dengue disease. the mosquito population is divided into subpopulations: winged form (mature female mosquitoes) and aquatic form (comprising eggs, larvae and pupae); the human population is divided into the subpopulations:susceptible, infected and removed (or immune). On the other hand we allow higher spatial dimensions and also parameters depending on space and time. is last generalization is done to cope with possible abiotic effects as variations in temperature, humidity, wind velocity, carrier capacities, and so on; thus, the results...
Compressive Sensing in Complex Networks with Topological Constraints
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
Compressive Sensing (CS) is a new paradigm in signal processing and information theory, which proposes to sample and compress sparse signals simultaneously and has drawn much attention in recent years. Many signals in lots of applications have a sparse representation in some bases, so CS is used as an efficient way of data compression in many applications such as image processing and medical applications in the last couple of years. Since some of the distributed information in complex networks are compressible too, CS can be used in order to gather the distribted information on the nodes or links efficiently. Traffic analysis and performance monitoring in computer networks, topology...
UCS-NT: An unbiased compressive sensing framework for Network Tomography
, Article ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings ; 2013 , Pages 4534-4538 ; 15206149 (ISSN) ; 9781479903566 (ISBN) ; Rabiee, H. R ; Hashemifar, Z. S ; Sharif University of Technology
2013
Abstract
This paper addresses the problem of recovering sparse link vectors with network topological constraints that is motivated by network inference and tomography applications. We propose a novel framework called UCS-NT in the context of compressive sensing for sparse recovery in networks. In order to efficiently recover sparse specification of link vectors, we construct a feasible measurement matrix using this framework through connected paths. It is theoretically shown that, only O(k log(n)) path measurements are sufficient for uniquely recovering any k-sparse link vector. Moreover, extensive simulations demonstrate that this framework would converge to an accurate solution for a wide class of...
NETAL: A new graph-based method for global alignment of protein-protein interaction networks
, Article Bioinformatics ; Volume 29, Issue 13 , 2013 , Pages 1654-1662 ; 13674803 (ISSN) ; Khadem, A ; Hashemifar, S ; Arab, S. S ; Sharif University of Technology
2013
Abstract
Motivation: The interactions among proteins and the resulting networks of such interactions have a central role in cell biology. Aligning these networks gives us important information, such as conserved complexes and evolutionary relationships. Although there have been several publications on the global alignment of protein networks; however, none of proposed methods are able to produce a highly conserved and meaningful alignment. Moreover, time complexity of current algorithms makes them impossible to use for multiple alignment of several large networks together.Results: We present a novel algorithm for the global alignment of protein-protein interaction networks. It uses a greedy method,...
The barrier effect of a WxTa(1-x) nanolayer on formation of single-texture CoSi2 on Si(1 0 0)
, Article Semiconductor Science and Technology ; Volume 21, Issue 8 , 2006 , Pages 1181-1192 ; 02681242 (ISSN) ; Moshfegh, A. Z ; Hashemifar, S. J ; Azimirad, R ; Sharif University of Technology
2006
Abstract
We have studied the phase formation of a CoSi2 layer by solid-state reaction of ternary Co/WxTa(1-x)/Si(1 0 0) systems. The effect of cosputtered WxTa(1-x) nanometric interlayers, with different values of x (0, 0.25, 0.5, 0.75 and 1), on the degree of texturing of a CoSi2 layer and disilicide formation of the refractory metals has been investigated. The annealed samples, in a temperature range of 400-1000 °C, were analysed by x-ray diffraction, sheet resistance measurement, scanning electron microscopy, and energy-dispersive x-ray techniques. Using W0.25Ta0.75 and W interlayers, the best (1 0 0) texture of the CoSi2 layer with a thermal stability in the range of 900-1000 °C was produced. In...
Single-crystalline growth of CoSi 2 by refractory-interlayer- mediated epitaxy
, Article Applied Surface Science ; Volume 233, Issue 1-4 , 2004 , Pages 123-128 ; 01694332 (ISSN) ; Moshfegh, A. Z ; Hashemifar, S. J ; Azimirad, R ; Sharif University of Technology
Elsevier
2004
Abstract
Single-crystal epitaxial quality of CoSi 2 films grown on Si(100) by refractory-interlayer-mediated epitaxy has been investigated. Thin layers of 10 nm co-sputtered W x Ta (1-x) , as refractory metal interlayers deposited on the Si, were followed by 25 nm of evaporated Co layer. The fabricated Co/W x Ta (1-x) /Si(100) systems were annealed in a temperature range from 400 to 1000°C in an N 2 (80%) + H 2 (20%) ambient for 1h. The annealed samples were analyzed and compared by sheet resistance measurement, X-ray diffraction, scanning electron microscopy, and wavelength dispersive spectroscopy techniques. In Co/W 0.25 Ta 0.75 /Si(100) system, with the best thermal stability, the grown CoSi 2...
Rcci Curvature for Metric-Measure Space via Optimal Transport
, M.Sc. Thesis Sharif University of Technology ; Bahraini, Alireza (Supervisor) ; Ranjbar Motlagh, Alireza (Co-Advisor)
Abstract
One of the important questions in mathematics is generalized. In case of metric spaces, one of the questions is: Can we extend notions of Riemannian geometry to arbitrary metric spaces smoothly? Ricci curvature is one of the most important concepts in differential geometry. Ricci curvature is defined for the Riemannian manifold and has many applications in mathematics and physics like Einstein’s equation in relativity theory. There is a good notion for a metric space having “sectional curvature bounded below by K” or “sectional curvature bounded above by K”, due to Alexandrov. Can we define the concept of Ricci curvature in metric space? A motivation for this question comes from Gromov’s...
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Seismic design codes reduce loads by using response modification factor. Because of the reserved strength in structural elements and capacity of structure to dissipate energy, structures can be designed for lower seismic loads. This factor has modified over time. In this thesis, the effect of the reduction in behavior factor on the response of two kinds of reinforced concrete systems were evaluated. Moment resisting frames and dual systems with different heights and regularity in plan, heve been design according to the behavior factor which is recommended in the 3rd edition of the Iranian codes of practice for seismic resistance design of buildings (Standard No. 2800). Drift and...
Prediction of Financial Markets Using Combination of Artificial Intelligence and Technical Analysis
, M.Sc. Thesis Sharif University of Technology ; Haji, Alireza (Supervisor)
Abstract
Generally, nowadays, machine learning methods are used in many different areas for their superiority over other methods of prediction. Although being a tough task, stock market prediction with machine learning approaches is being spread due to satisfying results published ever yday. Machine learning methods usually use varied kinds of data ,including structured data such as market data, technical indicators and some fundamental data as well as unstructured one entailing text and graph data in order to enhance their predictability capacity. In this thesis we aimed to find out more about the importance and the contribution of structured data in prediction and we tried to attain a framework...
, M.Sc. Thesis Sharif University of Technology ; Hajji, Alireza (Supervisor)
Abstract
This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve...
The Ricci Flow with Applications to the Poincare and Calabi Conjectures
, M.Sc. Thesis Sharif University of Technology ; Bahreini, Alireza (Supervisor)
Abstract
Poincare conjecture is one of the rst eorts for classifying 3-manifolds that was stated in the begining of 20th century. Eorts for proving this conjecture continued for about 100 years and nally Perelman has solved it in 2003. He has used Ricci ow which has been invented by Richard Hamilton in the early 80's. In this thesis rst we will introduce Ricci ow and will state the results before Perelman such as short time and long time existence of solution. Then we will mention some applications of Ricci ow and will state an explanation of the proof of uniformization and Calabi conjecture by Ricci ow. After that we start the main part of the thesis. In this part we will montion one of the...
Feasibility And Study(CNG Cylinder Production Plant)
, M.Sc. Thesis Sharif University of Technology ; Haji, Alireza (Supervisor)
Abstract
Nowadays best using of fossil fuels sources of the country (and) importance of comparison against lack of capacity in petrol production make determined the programmers and the directors to foresee and design expanded programs of the goals, to use natural gas for car fuels. To reach fulfillment of these programs, the confirmed needs of the natural gas cylinders are improved and make it essential to invest on producing compressive natural gas cylinders. In this way economical and technical change researches has been done in order to construct on department to produce 200,000 compressive natural gas cylinders in a year during two sets.(shifts) According to the results of technical researches...
Synthesis, Characterization and Field Emission Study of Molybdenum Oxide (MoOx)Nanostructures
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor)
Abstract
Different molybdenum oxide nano/micro structure thin films were synthesized by thermal evaporation method under various growth conditions such as deposition time, temperature and evaporation source-substrate distance. Molybdenum oxide nanostructures grown on Si(100) such as nanowalls, nanostars and nanowires were characterized with scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). Shape and type of nanostructures were determined with SEM, AFM and HRTEM analysis. XPS analysis showed that the synthesized nanostructures contained Mo6+, Mo5+, Mo4+ and...
Identification and Abnormal Condition Detection of a Cement Rotary Kiln
, M.Sc. Thesis Sharif University of Technology ; Fatehi, Alireza (Supervisor)
Abstract
One of the most important parts of a cement factory is the cement rotary kiln which plays a key role in quality and quantity of produced cement. In this part, the physical exertion and bilateral movement of air and materials, together with chemical reactions take place. Thus, this system has immensely complex and nonlinear dynamic equations. These equations have not worked out yet. Only in exceptional case; however, a large number of the involved parameters were crossed out and an approximation model was presented instead. This issue caused many problems for designing a cement rotary kiln controller. In this thesis, we employed a nonlinear system identification method for identification,...
Entanglement and Decoherence in Optomechanical Systems Coupled through Photothermal Effects
, Ph.D. Dissertation Sharif University of Technology ; Bahrampour, Alireza (Supervisor)
Abstract
Optomechanical systems have attracted considerable attention in the last decade. Such a raising prominence is mainly due to its capability in providing new insight into the quantum behavior of macroscopic objects and exploring the interface between quantum and classical mechanics. Alongside this fundamental quest, cavity optomechanics has many other benefits, ranging from very precise measurements on forces and positions to quantum information processing. In this thesis, we investigate quantum properties of such systems. Particularly, we study cooling of the mechanical resonator toward its ground state and the entanglement between this mechanical resonator and the cavity field. Cooling the...
Improvement in Reinforced Concrete Beam-Column Connections Behaviour using FRP Sheets
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In the last decade Fiber Reinforced Polymer (FRP) widely has been used to strengthening the reinforced concrete (RC) members. Most of...
Hodge Theory on Metric Spaces
, M.Sc. Thesis Sharif University of Technology ; Bahraini, Alireza (Supervisor)
Abstract
Hodge theory is a beautiful synthesis of geometry, topology, and anal- ysis, which has been developed in the setting of Riemannian manifolds. On the other hand, spaces of images, which are important in the math- ematical foundations of vision and pattern recognition, do not fit this framework. This motivates us to develop a version of Hodge theory on metric spaces with a probability measure. We believe that this constitutes a step towards understanding the geometry of vision. We extend the theory of the Laplacian on domains of Euclidean space or on a manifold and next to metric space. Finally we give a beautiful application in web researcher engin.
Behran Mehr Peyma's Activities Analysis
, M.Sc. Thesis Sharif University of Technology ; Miremadi, Alireza (Supervisor)
Abstract
Behran Mehr Peyma (BMP) is an elevator equipment producer and trader in Iran which was established in 2004. At first they are producing some regular parts of elevator and then during these years they are trying to improve their work and expand their business till they have the 15% market share in elevator market in Tehran.In this thesis I am trying to use the SWOT and PETS methods to show the exact situation of BMP comparing to the whole market considering the competitors.During this reduction in the market I suggest to BMP to change some policies and use some of its strength to attract some new customers, changing their brand name and find a relation to contribute in some tenders and...