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yoozbashi-zadeh--hossein
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Recovery of Gallium from Sodium Aluminate Solution in Bayer Process
, M.Sc. Thesis Sharif University of Technology ; Yoozbashi Zadeh, Hossein (Supervisor)
Abstract
Gallium is a rare and precious metal that is of particular importance in the electronics industry due to its use in semiconductors. This metal is partially present in bauxite ore. Around 70% of gallium go into sodium aluminate solution during the leaching of bauxite in the Bayer process. Gallium can be extracted from this solution, which is also called bayer solution, by several methods. Solvent extraction is one of the most common methods for recovery of gallium from Bayer's solution. Capabilities of this method for metals separation and concentrating of polymetallic solution, makes it suitable for many commercial and operational application. In present work, different substances used to...
Effect of Cu2+ on Leaching of Chalcopyrite in Chloride Media and Investigation of Thermodynamic and Kinetics of Process and Comparison with Sulfate Media
, M.Sc. Thesis Sharif University of Technology ; Yoozbashi Zadeh, Hossein (Supervisor)
Abstract
High advantages of hydrometallurgy have led to its recent development in metal extraction. Many investigations have been carried out on applying hydrometallurgy processes on copper extraction. In this study, Chalcopyrite concentrate produced in Sarcheshmeh copper plant was subjected to oxidative leaching investigation by cupric ion to determine the effect of several parameters on the copper and iron dissolution, included temperature of leaching, time of holding and cupric concentration as oxidant agent in a range of 38-97°C, 1.5-8.5 hours and 0.2-0.8 M respectively. The leaching media was chloride providing with 3M HCl 37% and CuCl2. The experiments were designed by central composite...
Production of (Nd,MM)2(Fe,Co,Ni)14B-type sintered magnets using a binary powder blending technique
, Article Journal of Alloys and Compounds, Lausanne ; Volume 298, Issue 1-2 , 2000 , Pages 319-323 ; 09258388 (ISSN) ; Kianvash, A ; Seyyed Reihani, M ; Yoozbashi Zadeh, H ; Sharif University of Technology
Elsevier Science S.A
2000
Abstract
The anisotropic (Nd,MM)2(Fe,Co,Ni)14B-type magnets were produced using the binary alloy sintering method (MM denotes a Misch-metal). The composition of the master alloy was close to stoichiometric Nd2Fe14B compound, while that of the sintering aid was MM38.2Co46.4Ni15.4. The microstructures of sintered magnets were investigated using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray detector (EDX). X-ray diffractometry (XRD) was also employed for phase analysis. The optimum magnetic properties were obtained for a composition of Nd11.9MM2.9Fe73.9Co3.3Ni1.1B6.9 made of 90 wt.% master alloy and 10 wt.% sintering aid. The two main phases, i.e. the (RE)2(TM)14B phase...
MR artifact reduction in the simultaneous acquisition of EEG and fMRI of epileptic patients
, Article 16th European Signal Processing Conference, EUSIPCO 2008, Lausanne, 25 August 2008 through 29 August 2008 ; 2008 ; 22195491 (ISSN) ; Sameni, R ; Jutten, C ; Hossein Zadeh, G. A ; Soltanian Zadeh, H ; Sharif University of Technology
2008
Abstract
Integrating high spatial resolution of functional magnetic resonance imaging (fMRI) and high temporal resolution of electroencephalogram (EEG) is promising in simultaneous EEG and fMRI analysis, especially for epileptic patients. The EEG recorded inside an MR scanner is interfered with MR artifacts. In this article, we propose new artifact reduction approaches and compare them with the conventional artifact reduction methods. Our proposed approaches are based on generalized eigenvalue decomposition (GEVD) and median filtering. The proposed methods are applied on experimental simultaneous EEG and fMRI recordings of an epileptic patient. The results show significant improvement over...
An iterative approach for reconstruction of arbitrary sparsely sampled magnetic resonance images
, Article 18th IEEE Symposium on Computer-Based Medical Systems, Dublin, Ireland, 23 June 2005 through 24 June 2005 ; 2005 , Pages 27-32 ; 10637125 (ISSN) ; Soleymani, M ; Hossein Zadeh, G. A ; Sharif University of Technology
2005
Abstract
In many fast MR imaging techniques, K-space is sampled sparsely in order to gain a fast traverse of K-space. These techniques use non-Cartesian sampling trajectories like radial, zigzag, and spiral. In the reconstruction procedure, usually interpolation methods are used to obtain missing samples on a regular grid. In this paper, we propose an iterative method for image reconstruction which uses the black marginal area of the image. The proposed iterative solution offers a great enhancement in the quality of the reconstructed image in comparison with conventional algorithms like zero filling and neural network. This method is applied on MRI data and its improved performance over other methods...
Determination of strain field and heterogeneity in radial forging of tube using finite element method and microhardness test
, Article Materials and Design ; Volume 38 , June , 2012 , Pages 147-153 ; 02641275 (ISSN) ; Saidi, P ; Karimi Taheri, A ; Hossein Zadeh, M ; Sharif University of Technology
2012
Abstract
Utilizing the Finite Element Method (FEM), the strain field in the radial forging process of tube is calculated at different process conditions and compared with the experimental results achieved using the microhardness test. The effect of various process parameters such as friction, axial feed, back push and front pull forces and die angles on the strain field are investigated. Using the results of the analysis, it is shown that the deformation inhomogeneity, introduced by an Inhomogeneity Factor (IF), is maximum in the inner zone of tube, while the minimum and the maximum effective strains are appeared at the inner zone of tube and about the core of the tube thickness, respectively. Also,...
Analytical Modeling of Oil Production from a Matrix Block by Free Fall Gravity Drainage
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Ghazanfari, Mohammad Hossein (Supervisor) ; Kharrat, Reyaz (Supervisor)
Abstract
Free fall gravity drainage is one of the most effective mechanisms of producing the oil from the matrix blocks in the gas invaded zone of the naturally fractured reservoirs. Although several analytical models have been proposed to characterize this mechanism in a matrix block, but these models suffer from the practical or theoretical viewpoints. In this study, a new analytical model was presented to predict the oil production rate versus time from a homogeneous matrix block under free fall gravity drainage mechanism. The model was developed by considering the balance between involved forces in the gas-oil gravity drainage process. By simplifying the equation derived from the momentum...
The maximum disjoint routing problem
, Article 22nd International Conference on Computing and Combinatorics, COCOON 2016, 2 August 2016 through 4 August 2016 ; Volume 9797 , 2016 , Pages 319-329 ; 03029743 (ISSN); 9783319426334 (ISBN) ; Sharif Zadeh, A. S ; Zarrabi Zadeh, H ; Sharif University of Technology
Springer Verlag
2016
Abstract
Motivated by the bus escape routing problem in printed circuit boards, we revisit the following problem: given a set of n axis-parallel rectangles inside a rectangular region R, find the maximum number of rectangles that can be extended toward the boundary of R, without overlapping each other. We provide an efficient algorithm for solving this problem in O(n2 log3 n log log n) time, improving over the current best O(n3)-time algorithm available for the problem
Learning overcomplete dictionaries from markovian data
, Article 10th IEEE Sensor Array and Multichannel Signal Processing Workshop, SAM 2018, 8 July 2018 through 11 July 2018 ; Volume 2018-July , 2018 , Pages 218-222 ; 2151870X (ISSN); 9781538647523 (ISBN) ; Esmaeili, S ; Babaie Zadeh, M ; Soltanian Zadeh, H ; Sharif University of Technology
IEEE Computer Society
2018
Abstract
We explore the dictionary learning problem for sparse representation when the signals are dependent. In this paper, a first-order Markovian model is considered for dependency of the signals, that has many applications especially in medical signals. It is shown that the considered dependency among the signals can degrade the performance of the existing dictionary learning algorithms. Hence, we propose a method using the Maximum Log-likelihood Estimator (MLE) and the Expectation Minimization (EM) algorithm to learn the dictionary from the signals generated under the first-order Markovian model. Simulation results show the efficiency of the proposed method in comparison with the...
Direction and Range Assignment for Directional Antennae in Wireless Networks
, M.Sc. Thesis Sharif University of Technology ; Zarrabi-Zadeh, Hamid (Supervisor)
Abstract
In recent years, significant interest has been attracted towards using directional antennae in wireless and sensor networks due to it’s decreased energy consumption, increased security and decreased radio wave overlapping. Substituting omni-directional antennae with directional antennae should be performed in a way that not only guarantees connectivity, but also minimizes radius and latency in network nodes. The problem is not polynomially solvable in general and effort has been made in recent years to present approximation algorithms to solve this problem. The approximation algorithms have been made possible using unit disk
graphs, Euclidean minimum spanning trees, grouping of...
graphs, Euclidean minimum spanning trees, grouping of...
Experimental study on macro segregation behavior in short and wide range solidification of different aluminum alloys
, Article Materials Science and Technology Conference and Exhibition 2013, MS and T 2013 ; Volume 2 , 2013 , Pages 822-829 ; 9781629933092 (ISBN) ; Mohammad Salehi, E ; Hassan Nejad, H ; Shafiei Zadeh, S ; Sharif University of Technology
2013
Abstract
Data are presented on the solidification of aluminum alloys and their macro segregation behavior. Three alloys with different solidification ranges were prepared in two temperatures. Two types of molds were also prepared by sand and metallic materials. The solidification of Al alloys were studied and the effects of four parameters were determined, including cooling rate, casting temperature, degassing and nucleation effects on solidification and a comparison was conducted to Scheil model performance. Three types of aluminum alloys (Al-12.1%Si, Al-6.9%Si and Al-4.4% Cu) with short, medium and wide solidification ranges were studied and the results showed that degassing, nucleation, increasing...
On the rectangle escape problem
, Article Theoretical Computer Science ; Volume 689 , 2017 , Pages 126-136 ; 03043975 (ISSN) ; Assadi, S ; Emamjomeh Zadeh, E ; Yazdanbod, S ; Zarrabi Zadeh, H ; Sharif University of Technology
2017
Abstract
Motivated by the bus escape routing problem in printed circuit boards, we study the following rectangle escape problem: given a set S of n axis-aligned rectangles inside an axis-aligned rectangular region R, extend each rectangle in S toward one of the four borders of R so that the maximum density over the region R is minimized. The density of each point p∈R is defined as the number of extended rectangles containing p. We show that the problem is hard to approximate to within a factor better than 3/2 in general. When the optimal density is sufficiently large, we provide a randomized algorithm that achieves an approximation factor of 1+ε with high probability improving over the current best...
A higher index theorem for foliated manifolds with boundary
, Article Bulletin des Sciences Mathematiques ; Volume 136, Issue 2 , 2012 , Pages 201-238 ; 00074497 (ISSN) ; Sharif University of Technology
2012
Abstract
Following Gorokhovsky and Lott and using an extension of the b-pseudodifferential calculus of Melrose, we give a formula for the Chern character of the Dirac index class of a longitudinal Dirac type operators on a foliated manifold with boundary. For this purpose we use the Bismut local index formula in the context of noncommutative geometry. This paper uses heavily the methods and technical results developed by E. Leichtnam and P. Piazza
A note on some classical results of Gromov-Lawson
, Article Proceedings of the American Mathematical Society ; Volume 140, Issue 10 , 2012 , Pages 3663-3672 ; 00029939 (ISSN) ; Sharif University of Technology
2012
Abstract
In this paper we show how the higher index theory can be used to prove results concerning the non-existence of a complete Riemannian metric with uniformly positive scalar curvature at infinity. By improving some classical results due to M. Gromov and B. Lawson we show the efficiency of these methods to prove such non-existence theorems
Delocalized betti numbers and morse type inequalities
, Article Rocky Mountain Journal of Mathematics ; Volume 41, Issue 4 , August , 2011 , Pages 1361-1374 ; 00357596 (ISSN) ; Sharif University of Technology
2011
Abstract
In this paper we state and prove delocalized Morse type inequalities for Morse functions as well as for closed differential 1-forms. These inequalities involve delocalized Betti numbers. As an immediate consequence, we prove the vanishing of delocalized Betti numbers of manifolds fibering over the circle under a vanishing condition on the delocalizing conjugacy class
Parallel in-vitro and in-vivo techniques for optimizing cellular microenvironments by implementing biochemical, biomechanical and electromagnetic stimulations
, Article Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS ; 2012 , Pages 1397-1400 ; 1557170X (ISSN) ; 9781424441198 (ISBN) ; Heibatollahi, M ; Ghafar Zadeh, E
2012
Abstract
Development of novel engineering techniques that can promote new clinical treatments requires implementing multidisciplinary in-vitro and in-vivo approaches. In this study, we have implemented microfluidic devices and in-vivorat model to study the mechanism of neural stem cell migration and differentiation.These studies can result in the treatment of damages to the neuronal system. In this research, we have shown that by applying appropriate ranges of biochemical and biomechanical factors as well as by exposing the cells to electromagnetic fields, it is possible to improve viability, proliferation, directional migration and differentiation of neural stem cells. The results of this study can...
On vanishing of low-degree higher Â-genera
, Article Differential Geometry and its Application ; Volume 43 , 2015 , Pages 56-59 ; 09262245 (ISSN) ; Sharif University of Technology
2015
Abstract
In this short note we apply methods introduced by B. Hanke and T. Schick to prove the vanishing of (low degree) higher Â-genera for spin manifolds admitting a positive scalar curvature metric. Our aim is to provide a short proof for this beautiful result
The Minimum vulnerability problem
, Article Algorithmica ; Volume 70, Issue 4 , 2014 , pp 718-731 ; ISSN: 14320541 ; Emamjomeh-Zadeh, E ; Norouzi-Fard, A ; Yazdanbod, S ; Zarrabi-Zadeh, H ; Sharif University of Technology
2014
Abstract
We revisit the problem of finding (Formula presented.) paths with a minimum number of shared edges between two vertices of a graph. An edge is called shared if it is used in more than one of the (Formula presented.) paths. We provide a (Formula presented.)-approximation algorithm for this problem, improving the best previous approximation factor of (Formula presented.). We also provide the first approximation algorithm for the problem with a sublinear approximation factor of (Formula presented.), where (Formula presented.) is the number of vertices in the input graph. For sparse graphs, such as bounded-degree and planar graphs, we show that the approximation factor of our algorithm can be...
The minimum vulnerability problem
, Article Algorithmica ; Volume 7676 LNCS , 2012 , Pages 382-391 ; 14320541(ISSN) ; 9783642352607 (ISBN) ; Emamjomeh Zadeh, E ; Norouzi Fard, A ; Yazdanbod, S ; Zarrabi Zadeh, H ; Sharif University of Technology
2012
Abstract
We revisit the problem of finding k paths with a minimum number of shared edges between two vertices of a graph. An edge is called shared if it is used in more than one of the k paths. We provide a ⌊k/2⌋-approximation algorithm for this problem, improving the best previous approximation factor of k - 1. We also provide the first approximation algorithm for the problem with a sublinear approximation factor of O(n3/4), where n is the number of vertices in the input graph. For sparse graphs, such as bounded-degree and planar graphs, we show that the approximation factor of our algorithm can be improved to O(√n). While the problem is NP-hard, and even hard to approximate to within an O(log n)...
Approximated Cramér-Rao bound for estimating the mixing matrix in the two-sensor noisy Sparse Component Analysis (SCA)
, Article Digital Signal Processing: A Review Journal ; Volume 23, Issue 3 , 2013 , Pages 771-779 ; 10512004 (ISSN) ; Babaie Zadeh, M ; Sharif University of Technology
2013
Abstract
In this paper, we address theoretical limitations in estimating the mixing matrix in noisy Sparse Component Analysis (SCA) in the two-sensor case. We obtain the Cramér-Rao Bound (CRB) error estimation of the mixing matrix based on the observation vector x=(x1,x2)T. Using the Bernoulli-Gaussian (BG) sparse distribution for sources, and some reasonable approximations, the Fisher Information Matrix (FIM) is approximated by a diagonal matrix. Then, the effect of off-diagonal terms in computing the CRB is investigated. Moreover, we compute an oracle CRB versus the blind uniform CRB and show that this is only 3 dB better than the blind uniform CRB. Finally, the CRB, the approximated CRB, the...