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dehghan-nayeri--ali
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Adaptive nonlinear observer design using feedforward neural networks
, Article Scientia Iranica ; Volume 12, Issue 2 , 2005 , Pages 141-150 ; 10263098 (ISSN) ; Alasty, A ; Sharif University of Technology
Sharif University of Technology
2005
Abstract
This paper concerns the design of a neural state observer for nonlinear dynamic systems with noisy measurement channels and in the presence of small model errors. The proposed observer consists of three feedforward neural parts, two of which are MLP universal approximators, which are being trained off-line and the last one being a Linearly Parameterized Neural Network (LPNN), which is being updated on-line. The off-line trained parts are able to generate state estimations instantly and almost accurately, if there are not catastrophic errors in the mathematical model used. The contribution of the on-line adapting part is to compensate the remainder estimation error due to uncertain parameters...
Protein Interaction Prediction Through Efficient FPGA and GPU Implementation
, M.Sc. Thesis Sharif University of Technology ; Koohi, Somayyeh (Supervisor)
Abstract
Alignment of genetic sequences is a fundamental part of genetic and bio-science. Alignment of DNA and protein sequences has an effective role in accelerating and simplifying problems in Bioinformatics like predicting protein interactions. Smith-Waterman algorithm is a precise algorithm for performing local alignment, suffering from computation complexity. There are some implementations on CPU, GPU, and FPGA platforms in order to reduce the run time of this algorithm. FPGA implementation is considered because of low power consumption and high degree of parallelism. With using pipeline and hardware redundancy techniques, various architectures have been proposed and implemented. In the best...
Neural optimal control of flexible spacecraft slew maneuver
, Article Acta Astronautica ; Volume 55, Issue 10 , 2004 , Pages 817-827 ; 00945765 (ISSN) ; Alasty, A ; Daneshjou, K ; Sharif University of Technology
2004
Abstract
This paper deals with the problem of optimal large-angle single-axis maneuvers of a flexible spacecraft with simultaneous vibration suppression of elastic modes. A spacecraft model with a cylindrical hub and one flexible appendage and tip mass is considered. Gravity gradient torque is considered as a disturbance torque. Multilayer perceptron neural networks are used to design a Neural Optimal Controller (NOC) for this multivariable non-linear maneuver. For NOC training, an off-line training procedure based on backpropagation through time algorithm is developed to minimize the general quadratic cost function in forward and backward pass stages. The proposed controller is also applicable to...
A Line Search Exact Penalty Method Using Steering Rules
, M.Sc. Thesis Sharif University of Technology ; Mahdavi Amiri, Nezamoddin (Supervisor)
Abstract
Exact linear search algorithm recently have been proposed in the literature by Byrd, Lopez-Calvaz and Nocedal for solving nonlinear programming problems. Line search algorithms for nonlinear programming problems must include safeguards to have global convergence properties. We explain an exact penalization approach that extends the class of problems that can be solved with line search SQP methods. In the algorithm, the penalty parameter is adjusted at every iteration to ensure sufficient progress in linear feasibilility and to promote acceptance of the step. A trust region is used to assist in the determination of the penalty parameter. It is shown that the algorithm enjoys favorable...
A New Method for Suboptimal Control of a Class of Non-Linear Systems
, M.Sc. Thesis Sharif University of Technology ; Hesaaraki, Mahmoud (Supervisor)
Abstract
In this thesis, a new non-linear control synthsis technique (θ - D) approximation) is discussed. This approach achieves suboptimal solutions to a class of non-linear optimal control problems characterized by a quadratic cost function and a plant model that is a_ne in control. An approximate solution to the Hamilton-Jacobi-Bellman (HJB) equation is sought by adding perturbations to the cost function. By manipulating the perturbation terms both asymptotic stability and suboptimality properties are obtained. The new technique overcomes the large-control-for-large-initial-states problem that occurs in some other Taylor series expansion based methods. Also this method does not require excessive...
Nonlinear Response of Shear-Flexural MDOF Structures Subjected to Seismic Excitations
, M.Sc. Thesis Sharif University of Technology ; Ghannad, Mohammad Ali (Supervisor)
Abstract
A generic single-span frame has been used to represent a shear-flexural building and the degree of participation of overall shear and flexural behavior in mode shapes, is controlled by dimensionless parameters of α, δk and δp. By evaluation of modal analysis results, one may conclude the extent to which each parameter affects the dominancy of shear/flexural behavior. By understanding the relation between the abovementioned parameters and proportion of shear/flexural behavior of structures, effects of these parameters and consequently trend of modal shapes on the nonlinear analyses results would be investigated. According to nonlinear analyses results of the flexural structures, ductility...
An Investigation into the Kinetics of Dynamic Recrystallization of Fe-Ni Alloy
, M.Sc. Thesis Sharif University of Technology ; Karimi Taheri , Ali (Supervisor) ; Abbasi, Mehdi (Supervisor)
Abstract
The A-286 superalloy is an iron-nickel base alloy having properties such as oxidation resistance and high mechanical strength. In addition, good producibility and high workability are the important properties of this alloy. In the present work dynamic restoration mechanism of A-286 supper alloy during thermo-mechanical processing has been studied. The aim is to verify the dominant restoration mechanism in different deformation conditions and also to determine the desire deformation parameters for hot rolling. In this regard, utilizing compression test in the range of 950 to 1100ºC and strain rate of 0.001 to 1 per second, the strain-stress curve for this alloy was obtained. After correction...
Synthesis of Homo and Hetero Bi and Multinuclear Complexes Containing Gold and Closed-Shell Metals Using Bridging Phosphine and Pyridine Ligands and Study of Their Emission Properties
, Ph.D. Dissertation Sharif University of Technology ; Jamali, Sirous (Supervisor)
Abstract
In this project, multi-nucleated clusters of copper (I)-gold (I) and silver (I)-gold (I) were synthesized. Initially, two tetranuclear Au2Cu2 cluster complexes [Au2Cu2(μ-(PPh2)2py)2(μ-OH)](PF6)3, and [Au2Cu2Cl2(μ-(PPh2)2 py)2](OTf)2, have been prepared by the reactions of precursor complexes [Au2(μ-(PPh2)2py)2](OTf)2, and [Cu2(μ-(PPh2)2py)2(μ-SMe2)(OTf)2], with [Cu(NCCH3)4]PF6 and AuCl(SMe2), respectively. The crystal structures of two clusters were determined by X-ray crystallography, indicating a butterfly-shaped Au2Cu2 metal core for the first and a planar-shaped Au2Cu2 metal core for second cluster. In the first cluster, the Cu atoms occupy the edge-sharing bond, while in the second...
Experimental and Theoretical Investigation of Heavy Oil Recovery Using Chemical Flooding; Mechanistically Study
, Ph.D. Dissertation Sharif University of Technology ; Masihi, Mohsan (Supervisor) ; Ayatollahi, Shahaboddin (Supervisor)
Abstract
Chemical flooding has great potential to recover significant fractions of remaining oil for medium to heavy oil reservoirs not applicable for thermal recovery techniques. Nowadays, with gradual crude oil price increase the chemical process is receiving renewed attention, however, illustration of the possibility of various chemical injection scenarios for medium to heavy oil reservoirs has not been clearly reported and these kinds of reservoirs require more investigation for the applicability of these techniques in the fields. The interfacial active molecules are responsible for providing low IFT range and water/oil emulsions which in many cases could improve the oil displacement efficiency....
Tetranuclear Au2Cu2 clusters with butterfly- and planar-shaped metal cores: strong rigidochromism induced by jahn-teller distortion in two-coordinated gold(I) centers
, Article Inorganic Chemistry ; Volume 58, Issue 18 , 2019 , Pages 12122-12131 ; 00201669 (ISSN) ; Jamali, S ; Jamjah, A ; Samouei, H ; Sharif University of Technology
American Chemical Society
2019
Abstract
Two tetranuclear Au2Cu2 cluster complexes [Au2Cu2(μ-(PPh2)2py)2(μ-OH)](PF6)3, 2, and [Au2Cu2Cl2(μ-(PPh2)2 py)2](OTf)2, 4, have been prepared by the reactions of precursor complexes [Au2(μ-(PPh2)2py)2](OTf)2, 1, and [Cu2(μ-(PPh2)2py)2(μ-SMe2)(OTf)2], 3, with [Cu(NCCH3)4]PF6 and AuCl(SMe2), respectively. The crystal structures of complexes 2 and 4 were determined by X-ray crystallography, indicating a butterfly-shaped Au2Cu2 metal core for 2 and a planar-shaped Au2Cu2 metal core for 4. In complex 2, the Cu atoms occupy the edge-sharing bond, while in complex 4, alternating Au and Cu atoms occupy the tetragon vertices. The optical properties of the complexes were investigated by experimental...
An Automatic Semantic Tagger Based on USAS for the Persian Language
, M.Sc. Thesis Sharif University of Technology ; Rahimi, Saeed (Supervisor) ; Bahrani, Mohammad (Supervisor)
Abstract
The emergence of lexical knowledge bases such as WordNet and FarsNet foregrounded the importance of semantic annotation of words in the areas of natural language processing and corpus linguistics. The methodology in these knowledge bases is based on semantic relations and dictionary definitions of the words in coverage. Another efficient way to perform semantic annotation is by semantically classifying the lexicon of a language in a taxonomy. In this research, we build a semantic annotation system for the semantic tagging of Persian texts. This system can be used for building tools and softwares for natural language processing in applications such as text summarization, plagiarism detection...
Upper bounds for the 2-hued chromatic number of graphs in terms of the independence number
, Article Discrete Applied Mathematics ; Volume 160, Issue 15 , 2012 , Pages 2142-2146 ; 0166218X (ISSN) ; Ahadi, A ; Sharif University of Technology
Elsevier
2012
Abstract
A 2-hued coloring of a graph G is a coloring such that, for every vertex v∈V(G) of degree at least 2, the neighbors of v receive at least two colors. The smallest integer k such that G has a 2-hued coloring with k colors is called the 2-hued chromatic number of G, and is denoted by χ2(G). In this paper, we will show that, if G is a regular graph, then χ2(G)-χ(G)≤2log 2(α(G))+3, and, if G is a graph and δ(G)<2, then χ2(G)-χ(G)≤1+4 Δ2δ-1⌉(1+log 2Δ(G)2Δ(G)-δ(G)(α(G))), and in the general case, if G is a graph, then χ2(G)-χ(G)≤2+min α′(G),α(G)+ω(G)2
Concept Drift Detection in Data Streams Using Ensemble Classifiers
, M.Sc. Thesis Sharif University of Technology ; Beigy, Hamid (Supervisor)
Abstract
Concept drift is a challenging problem in the context of data stream processing. As a result of increasing applications of data streams, including network intrusion detection, weather forecasting, and detection of unconventional behavior in financial transactions; numerous studies have been conducted in the field of concept drift detection. In order to solve the problem of concept drift detection, an ideal method should be able to quickly and correctly identify a variety of changes, adapt quickly to new concepts, in the presence of limitations of memory and processing power. In this thesis, a new explicit concept drift detection method based on ensemble classifiers has been proposed for data...
A New Approach Towards Modified Single Drop Microextraction Using Solvents with Densities Higher than Water
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
In the present work, the combination of single drop liquid phase microextraction and gas chromatography-mass detector (GC-MS) was used for determination of pesticides, Clodinafop, Haloxyfop and Fenoxyprop in natural water samples. a novel techniques based on SDME for develop in which solvents with higher density than water was successfully used. this technique could overcome some limitations of conventional SDME such as instability of organic droplet and limited stirrer rate in which result increasing the mass transfer rate and extraction efficiency. Experimental liquid phase microextraction (LPME) conditions, such as extracting solvent, stirring rate, micro drop volume, extraction time, pH...
Some Results and Conjectures on Bounds for Graph Colorings
, M.Sc. Thesis Sharif University of Technology ; Mahmoodian, Ebadollah (Supervisor)
Abstract
There are many ways to color the vertices and edges of graphs, such as, rainbow connection, vertex coloring and dynamic coloring. In this thesis, in Chapter 1 we introduce a new coloring, we consider its relationship with some other colorings and we investigate its computational complexity. In chapter 1, we focus on the proper orientation number. The problem of orienting the edges of a given simple graph so that the maximum indegree of vertices is minimized was introduced in 2004. We show that there is a polynomial time algorithm for determining the proper orientation number of a given 3-regular graph. But it is NP-complete to decide if the proper orientation number of a 4-regular graph is 3...
Experimental Study of a Side Intake in Transonic Speed
, M.Sc. Thesis Sharif University of Technology ; Farahani, Mohammad (Supervisor)
Abstract
This study aims to evaluate aerodynamic coefficients of an airplane with air breathing engine experimentally. In these experiments, an ejector is used to better simulate flying conditions and aerodynamic interferences generated in inlet and exhaust engine. Therefore, at first, an ejector was designed for simultaneous simulation of exit cold flow and inlet flow of engine. All tests were conducted at QRC Trisonic wind tunnel and at Mach number of 0.5 to 0.85, angles of -4 to 6 deg. and for various amounts of pressure ejector and control surfaces angles. Finally, for the Mach number of 0.5, effect of roughness on the aerodynamic coefficients was examined. The results showed that, drag...
Studying the Dependence Structure of Tehran Stock Exchange and Over-the-Counter Market by Using Constant and Time-Varying Conditional Copula Functions
, M.Sc. Thesis Sharif University of Technology ; Zamani, Shiva (Supervisor)
Abstract
In this thesis, we study the dependence structure between the Tehran Stock Exchange and over-the-counter market, as the two main Iranian capital market institutions. Several constant and time-varying conditional Copula functions are used to model this dependence structure from October 2009 to August 2014. It is shown that, compared to constant conditional copulas, time-varying conditional copulas, provide a better performance. Analyzing the conditional tail dependence of these indices shows an asymmetric dependence structure. Also, investigating the dynamic conditional correlation and conditional tail dependence, using time-varying conditional copulas, reveals large variations and an...
Concentration of Low Grade Zinc Carbonate ore of Anguran Mine by Froth Flotation
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
In this work feasibility of concentrating zinc carbonate ore from Anguran mine by froth flotation process has been studied. Potasium Amyl Xhantate and Oleic Acid have been studied as possible collectors. The initial tests indicate that oleic acid might be a better collector. Experimental were conducted to determined important factors and to optimize the process by careful control of the pulp chemical composition and flotation variables. A concentrate containing 24.9% zinc has been attained. The recovery of zinc in the concentrate is 76.1%.
Biomechanical Evaluation of the Niosh Equation in Stoop Versus Squat Load-Handling Activities Using a Full-Body Musculoskeletal Model
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor)
Abstract
Objective: To assess adequacy of the National Institute for Occupational Safety and Health (NIOSH) Lifting Equation (NLE) in controlling lumbar spine loads below their recommended action limits during load-handling activities in the stoop and squat using a detailed musculoskeletal model,that is, the AnyBody Modeling System.Background: The NIOSH committee employed simplistic biomechanical models for the calculation of the spine compressive loads with no estimates of the shear loads. In addition, NLE does not include the posture of the knee during manual material handling. It is therefore unknown whether the NLE would adequately control lumbar compression and shear loads below their...
Fabrication and Investigation of the Microscopic Structure and Mechanical Properties of Zx00 Magnesium Alloy by Applying the Multi-Directional Forging Process on Extruded and Homogenized Samples
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Magnesium and its alloys have gained significant attention in medical applications due to their good biocompatibility. However, their widespread use has been limited by some inherent drawbacks, such as poor mechanical properties. The ZX00 magnesium alloy has been used in medical applications, including implants, due to its slow degradation rate and good ossification. However, this alloy lacks sufficient strength and ductility. The severe plastic deformation method can create an ultrafine grain structure and improve mechanical properties. In this study, to improve the mechanical properties and create an ultrafine grain structure, the multi-directional forging process was performed on...