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Passive localization of stationary targets: In extremely noisy conditions and asymmetric paths
, Article ISPACS 2012 - IEEE International Symposium on Intelligent Signal Processing and Communications Systems ; 2012 , Pages 385-389 ; 9781467350815 (ISBN) ; Sharif University of Technology
Abstract
A new method for position determination of stationary targets from radio bearings, using triangulation, and based on the partial derivative analysis of bearing error has been proposed. Mathematical derivations have been carried out and a simulation illustrating the effectiveness of the method has been run. It turns out that, the method works best when the noise is excessively high and the traversed path is asymmetric. In such conditions, the method illustrates an error reduction of up to 5% with respect to the Least Square algorithm
Gold extraction from an oxide ore in iodine-iodide solutions
, Article Industrial Electrochemistry and Electrochemical Engineering General Session - 220th ECS Meeting, Boston, MA, 9 October 2011 through 14 October 2011 ; Volume 41, Issue 17 , 2012 , Pages 53-60 ; 19385862 (ISSN) ; 9781607683070 (ISBN) ; Sharif University of Technology
Abstract
Two types of gold ores were subjected to iodide/iodine leaching at room temperature. The effects of three factors, including ore type (a carbonaceous and an oxide gold ores), iodide/iodine concentration, and the presence of oxygen in solution on gold leaching performance were investigated. The carbonaceous ore showed only 20% gold extraction into the solution; since gold-iodide complexes would readily adsorb on organic matter. In contrast, gold extraction from the oxide ore in a solution containing 20 g/L iodide and 4 g/L iodine reached 77% in 6 h and 89% in 24 h. With iodate as the oxidant, no gold could be leached in 48 hours. When the iodate was partially converted to iodine by adding HCl...
Performance of circular opening in beam web connections
, Article Life Science Journal ; Volume 9, Issue 3 , 2012 , Pages 1377-1383 ; 10978135 (ISSN) ; Sharif University of Technology
Abstract
Fragile behavior in the area around the connections which is tangent on beam to column and also incidence of brittle cracks and failures in this area, in the event of severe ground shaking, are the main problems and disadvantages that have negative effect on the performance of steel bending frames and would have restrictions effect on the of the frame's plasticity behavior. To solve the problem of bending the frame, two methods have been proposed. In the first method, the connection will be strengthened so that has enough resistance and sufficient strength to prevent cracks and failures to non-elastic deformation of the frame in the inner part of beams be answered. In the second method,...
The effect of geometrical properties of reservoir shale barriers on the performance of Steam-assisted Gravity Drainage (SAGD)
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 34, Issue 23 , 2012 , Pages 2178-2191 ; 15567036 (ISSN) ; Sharif University of Technology
Abstract
Many bitumen reservoirs contain shale layers of varying thickness, lateral extent, and frequency. These shale layers, depending on their size, vertical and horizontal locations, and continuity throughout the reservoir, may act as a flow barrier and severely reduce vertical permeability of the pay zone and slow down the steam-assisted gravity drainage steam chamber development. Therefore, to improve productivity in these reservoirs, understanding of the effects of reservoir heterogeneities has become necessary. This work presents numerical investigation of the effects of shale barriers on steam-assisted gravity drainage performance when applied to produce mobile heavy oil. The most concern of...
Hydrogen management in refineries
, Article Petroleum and Coal ; Volume 54, Issue 4 , 2012 , Pages 357-368 ; 13377027 (ISSN) ; Sharif University of Technology
2012
Abstract
Environmental restrictions, new transportation fuel specifications, and increased processing of heavier more-sour curds are leading substantial increases in refinery hydrogen consumption for hydrodesulfurisation, aromatic and olefin saturation and improvement of product quality and reduces in refinery hydrogen production from catalytic reformers as a by-product. Therefore above factors make hydrogen management, a critical issue. Generating, recovering and purchasing of hydrogen have significant impact on refinery operating costs. More importantly, overall refinery operations, may be constrained by the availability of hydrogen. Primary consideration, however, should be given to the recovery...
Concavity degree: A new feature for chromosome centromere localization
, Article AISP 2012 - 16th CSI International Symposium on Artificial Intelligence and Signal Processing ; 2012 , Pages 58-63 ; 9781467314794 (ISBN) ; Sharif University of Technology
2012
Abstract
Analyzing the features of the chromosomes can be very useful for diagnosis of many genetic disorders or prediction of the possible abnormalities that may occur in the future generations. For this purpose, karyotype is often used which to make it, there is necessary to identify each one of the 24 chromosomes from the microscopic images. Definition and extraction of the morphological and band pattern based features for each chromosome is the first step to identify them. An important class of the morphological features is the location of the chromosome's centromere. Thus, centromere localization is an initial step in designing an automatic karyotyping system. In this paper, a novel algorithm...
The regulated market for kidneys in Iran
, Article Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, 22 August 2011 through 23 August 2011 ; Volume 80 LNICST , August , 2012 , Pages 62-75 ; 18678211 (ISSN) ; 9783642309120 (ISBN) ; Sharif University of Technology
2012
Abstract
We study the kidney market in Iran. The most effective treatment for end-stage renal disease is a kidney transplant. While the supply of cadaveric kidneys is limited, the debate has been focused on the effects of the existence of a free market for human organs. Economists as well as medical and legal researchers are divided over the issue. Iran has a unique kidney market which has been in place for over 20 years, frequently reporting surprising success in reducing the waiting list for kidneys. This paper demonstrates how the Iranian system works
Analysis and characterization of phase evolution of nanosized BaTiO 3 powder synthesized through a chemically modified sol-gel process
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 43, Issue 11 , November , 2012 , Pages 4414-4426 ; 10735623 (ISSN) ; Sharif University of Technology
2012
Abstract
In the current research, a cost-effective and modified method with a high degree of reproducibility was proposed for the preparation of fine nanoscale and high-purity BaTiO3. In contrast to the other established methods, in this research, carbonate-free BaTiO3 nanopowders were prepared at a lower temperature and in a shorter time span. To reach an in-depth understanding of the scientific basis of the proposed process, an in-detail analysis was carried out for characterization of nanoscale BaTiO3 particles via differential thermal analysis (DTA)/thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and...
Using three different optical fiber designs to study humidity effect on the air refractive index
, Article Optics and Lasers in Engineering ; Volume 50, Issue 11 , November , 2012 , Pages 1495-1500 ; 01438166 (ISSN) ; Sharif University of Technology
2012
Abstract
Design and operation of three different optical designs based on the light intensity modulation for investigation of the humidity effects on the air index of refraction are described. The measurement variable is the transmitted power, which depends on the refractive index of the medium in the path of a fiber-to-fiber optical design. Three different probes (probe #1, #2, and #3) are tested in which probe #1 and probe #2 can also check the presence of water or any other transparent liquid in the gap between the two axial fibers. Performances of the new systems are tested as a refractive index monitoring mean and experimental results are given. The variations of the modulated powers as...
Comments on chaos synchronization of uncertain fractional-order chaotic systems with time delay based on adaptive fuzzy sliding mode control
, Article IEEE Transactions on Fuzzy Systems ; Volume 20, Issue 5 , February , 2012 , Pages 993-995 ; 10636706 (ISSN) ; Sharif University of Technology
2012
Abstract
In this letter, it is shown that some of the equalities that were used in the proof of the main theorem of the paper given by Lin and Lee are not consistent with fractional calculus principles. Simple counterexamples are provided to confirm this point. Moreover, correct versions of equations that were derived in the mentioned theorem are presented. Based on these corrections, the synchronization scheme proposed in the mentioned paper is investigated
Iterative method for frequency updating of simple vibrating system
, Article Journal of Vibroengineering ; Volume 14, Issue 3 , 2012 , Pages 1370-1377 ; 13928716 (ISSN) ; Sharif University of Technology
JVE
2012
Abstract
Iterative methods for modification of vibratory characteristics of dynamic systems have attracted a lot of attention as a convenient and more economical way when compared to the traditional and costly structural dynamic optimization processes. Many complicated structures, such as telecommunication towers, chimneys and tall buildings, may be modeled as simple spring-mass systems. This paper presents an iterative method for modification of the frequencies of simple vibrating system consisting of springs and masses. The proposed algorithm may be used to adjust any of the vibration frequencies of a simple vibrating system to the target values within the desired level of accuracy. The method...
Numerical assessment of a double step integration algorithm for J 2 plasticity with Armstrong-Frederick evolution of back stress
, Article Scientia Iranica ; Volume 19, Issue 5 , 2012 , Pages 1168-1179 ; 10263098 (ISSN) ; Sharif University of Technology
2012
Abstract
In this work a double step algorithm is presented for the integration of equations governing the behavior of von Mises material in plastic limit. The isotropic and kinematic hardenings employed are of general type and the evolution of back stress follows the Armstrong-Frederick rule. Theoretical and numerical aspects are discussed in detail and a comparison is made with the classical backward Euler method
From traditional to fractional PI control: A key for generalization
, Article IEEE Industrial Electronics Magazine ; Volume 6, Issue 3 , 2012 , Pages 41-51 ; 19324529 (ISSN) ; Sharif University of Technology
IEEE
2012
Abstract
Proportional-integral (PI) controllers are the most common form of feedback used in industrial applications today [1][3]. The use of proportional and integral feedback also has a long history of practical applications [4]. For example, in the middle of the 18th century, centrifugal governors as the proportional feedback were applied to regulate the speed of windmills [5]. By the 19th century, it was known that using integral feedback could remove the offsets appearing in working with governors [6]. At present, PI control, still a very basic form of feedback, is also one of the first solutions often considered in the control of industrial systems [7]. On the other hand, in some applications,...
Collective behavior of interacting locally synchronized oscillations in neuronal networks
, Article Communications in Nonlinear Science and Numerical Simulation ; Volume 17, Issue 10 , 2012 , Pages 3922-3933 ; 10075704 (ISSN) ; Sharif University of Technology
Elsevier
2012
Abstract
Local circuits in the cortex and hippocampus are endowed with resonant, oscillatory firing properties which underlie oscillations in various frequency ranges (e.g. gamma range) frequently observed in the local field potentials, and in electroencephalography. Synchronized oscillations are thought to play important roles in information binding in the brain. This paper addresses the collective behavior of interacting locally synchronized oscillations in realistic neural networks. A network of five neurons is proposed in order to produce locally synchronized oscillations. The neuron models are Hindmarsh-Rose type with electrical and/or chemical couplings. We construct large-scale models using...
On a non-equilibrium statistical mechanics of graph homomorphisms
, Article Advanced Studies in Theoretical Physics ; Volume 6, Issue 17-20 , 2012 , Pages 815-821 ; 1313311 (ISSN) ; Sharif University of Technology
HIKARI
2012
Abstract
Inspired by the paper [1] we develop a non-equilibrium statistical mechanics for graph homomorphisms, which can be considered as a generalization of several other Markov processes including Ising and parallel Hopfield models. We then apply the theory for the special case of homo-morphisms between rings with N nodes and derive the associated classical Lagrangian in the large N limit
A simple consensus algorithm for distributed averaging in random geographical networks
, Article Pramana - Journal of Physics ; Volume 79, Issue 3 , August , 2012 , Pages 493-499 ; 03044289 (ISSN) ; Sharif University of Technology
2012
Abstract
Random geographical networks are realistic models for wireless sensor networks which are used in many applications. Achieving average consensus is very important in sensor networks and the faster the consensus is, the durable the sensors' life, and thus, the better the performance of the network. In this paper we compared the performance of a number of linear consensus algorithms with application to distributed averaging in random geographical networks. Interestingly, the simplest algorithm - where only the degree of receiving nodes is needed for the averaging - had the best performance in terms of the consensus time. Furthermore, we proved that the network has guaranteed convergence with...
The dynamic pull-in instability and snap-through behavior of initially curved microbeams
, Article Mechanics of Advanced Materials and Structures ; Volume 19, Issue 6 , Jul , 2012 , Pages 485-491 ; 15376494 (ISSN) ; Sharif University of Technology
T&F
2012
Abstract
In this study, dynamic pull-in instability and snap-through buckling of initially curved microbeams are investigated. The microbeams are actuated by suddenly applied electrostatic force. A finite element model is developed to discretize the governing equations, and Newmark time discretization is employed to solve the discretized equations. The static pull-in behavior is investigated to validate the model. The results of the finite element model are compared with finite difference solutions and their convergence is examined. In addition, the influence of different parameters on dynamic pull-in instability and snap-through buckling is explored
Determination of flow stress under hot deformation conditions
, Article Materials Science and Engineering A ; Volume 552 , 2012 , Pages 566-568 ; 09215093 (ISSN) ; Sharif University of Technology
2012
Abstract
In order to predict the flow stress curves up to peak under the hot working conditions two crucially modified models are presented. The modification is done by considering the effects of both temperature and strain rate. Besides, the ability of prediction at very low strains is added to them. Furthermore a new mathematical model has been developed to estimate the stress-strain curves beyond the peak via a secant hyperbolic function. The predicted results are found to be in accord with empirical values
Being a teaching assistant can play an important role in your future career
, Article IEEE Potentials ; Volume 31, Issue 4 , 2012 , Pages 15-16 ; 02786648 (ISSN) ; Sharif University of Technology
2012
Abstract
Reza Aminzadeh talks about the benefits of being a teaching assistant (TA), who assist a faculty member during the teaching of a course by providing additional teaching resources to enhance the quality of instructions for students. A TA can also be an undergraduate student. The duties of a TA range from common tasks including grading, holding office hours, and writing exams. Serving as a TA teaches an engineer a lot of things. It improves their skills and abilities and helps them to perform better in their future academic career. Undergraduate students serving as TAs have the advantage of participating in classroom and teaching activities. This provides them a set of instructional skills...
Second order integration algorithms for j2 plasticity with generalized isotropic/kinematic hardening
, Article Asian Journal of Civil Engineering ; Volume 13, Issue 2 , April , 2012 , Pages 203-232 ; 15630854 (ISSN) ; Sharif University of Technology
AJCE
2012
Abstract
In this work four algorithms are presented for the integration of equations governing the behavior of von Mises material in plastic limit. Two of them are single-step and the others are double-step algorithms. Single-step algorithms are straight forward extension of backward Euler method or midpoint rule while double-step algorithms are a combination of two. In past similar algorithms were proposed for special cases of isotropic/kinematic hardening; however the algorithms presented in this work are applicable to general isotropic/kinematic hardening laws. Theoretical as well as numerical aspects are presented for all integration schemes and elaborated for double-step algorithms which are...