Showing papers by "Amirkabir University of Technology published in 2007"

LRP6 Mutation in a Family with Early Coronary Disease and Metabolic Risk Factors

Abstract: Coronary artery disease (CAD) is the leading cause of death worldwide and is commonly caused by a constellation of risk factors called the metabolic syndrome. We characterized a family with autosomal dominant early CAD, features of the metabolic syndrome (hyperlipidemia, hypertension, and diabetes), and osteoporosis. These traits showed genetic linkage to a short segment of chromosome 12p, in which we identified a missense mutation in LRP6, which encodes a co-receptor in the Wnt signaling pathway. The mutation, which substitutes cysteine for arginine at a highly conserved residue of an epidermal growth factor-like domain, impairs Wnt signaling in vitro. These results link a single gene defect in Wnt signaling to CAD and multiple cardiovascular risk factors.

A Review of Methods for Synthesis of Nanostructured Metals with Emphasis on Iron Compounds

Abstract: Synthesis of metal nanoparticles with specific properties is a newly established research area attracting a great deal of attention. Several methods have been put forward for synthesis of these materials, namely chemical vapor condensation, arc discharge, hydrogen plasma—metal reaction, and laser pyrolysis in the vapor phase, microemulsion, hydrothermal, sol-gel, sonochemical, and microbial processes taking place in the liquid phase, and ball milling carried out in the solid phase. The properties of metal nanoparticles depend largely on their synthesis procedures. In this paper the fundamentals, advantages, and disadvantages of each synthesis method are discussed.

A numerical method for two-dimensional Schrödinger equation using collocation and radial basis functions

Abstract: In this paper, we propose a numerical scheme to solve the two-dimensional (2D) time-dependent Schrodinger equation using collocation points and approximating the solution using multiquadrics (MQ) and the Thin Plate Splines (TPS) Radial Basis Function (RBF). The scheme works in a similar fashion as finite-difference methods. The results of numerical experiments are presented, and are compared with analytical solutions to confirm the good accuracy of the presented scheme.

The one-dimensional heat equation subject to a boundary integral specification

Abstract: Various processes in the natural sciences and engineering lead to the nonclassical parabolic initial boundary value problems which involve nonlocal integral terms over the spatial domain. The integral term may appear in the boundary conditions. It is the reason for which such problems gained much attention in recent years, not only in engineering but also in the mathematics community. In this paper the problem of solving the one-dimensional parabolic partial differential equation subject to given initial and nonlocal boundary conditions is considered. Several approaches for the numerical solution of this boundary value problem which have been considered in the literature, are reported. New finite difference techniques are proposed for the numerical solution of the one-dimensional heat equation subject to the specification of mass. Numerical examples are given at the end of this paper to compare the efficiency of the new techniques. Some specific applications in various engineering models are introduced.

Solution of the fully fuzzy linear systems using iterative techniques

Abstract: This paper mainly intends to discuss the iterative solution of fully fuzzy linear systems which we call FFLS. We employ Dubois and Prade’s approximate arithmetic operators on LR fuzzy numbers for finding a positive fuzzy vector x ˜ which satisfies A ∼ x ˜ = b ∼ , where A ∼ and b ∼ are a fuzzy matrix and a fuzzy vector, respectively. Please note that the positivity assumption is not so restrictive in applied problems. We transform FFLS and propose iterative techniques such as Richardson, Jacobi, Jacobi overrelaxation (JOR), Gauss–Seidel, successive overrelaxation (SOR), accelerated overrelaxation (AOR), symmetric and unsymmetric SOR (SSOR and USSOR) and extrapolated modified Aitken (EMA) for solving FFLS. In addition, the methods of Newton, quasi-Newton and conjugate gradient are proposed from nonlinear programming for solving a fully fuzzy linear system. Various numerical examples are also given to show the efficiency of the proposed schemes.

Numerical solution of the Klein–Gordon equation via He’s variational iteration method

Abstract: In this paper, we present the solution of the Klein--Gordon equation. Klein--Gordon equation is the relativistic version of the Schrodinger equation, which is used to describe spinless particles. The He’s variational iteration method (VIM) is implemented to give approximate and analytical solutions for this equation. The variational iteration method is based on the incorporation of a general Lagrange multiplier in the construction of correction functional for the equation. Application of variational iteration technique to this problem shows rapid convergence of the sequence constructed by this method to the exact solution. Moreover, this technique reduces the volume of calculations by avoiding discretization of the variables, linearization or small perturbations.

Salt Free Reactive Dyeing of Cationized Cotton

Abstract: In this study 3-chloro-2-hydroxypropyltrimethylammonium chloride was used as a cationic agent to cationize cotton fabric by a pad-batch process. The cationized cotton samples were dyed with different reactive dyes containing various reactive groups. The dyeability of the cationized cotton samples with reactive dyes without salt was significantly improved due to an increase in the ionic attraction between the dye and cationized cotton. The results showed that the wash and dry rubbing fastness of the cationized cotton dyed with different reactive dyes are similar to those of the untreated cotton. However, the light fastness of some of the cationized fabric samples was improved.

Simultaneous x-linking and antimicrobial finishing of cotton fabric

Abstract: This research work tries to achieve a multifunctional finishing on the cotton fabric by using environmentally friendly chemicals. Chitosan and N-(2-hydroxy) propyl-3-trimethyl ammonium chitosan chloride (HTCC) with different crosslinking agents including citric acid (CA), butane tetra carboxylic acid (BTCA), and glutaraldehyde (GA) were coapplied on the cotton fabric. This improves the laundering durability of antimicrobial treatment by formation of covalent bond between the crosslinking agent, antimicrobial agent, and cellulosic chains. Furthermore, it helps to enhance the crease resistance properties of the treated samples. The antimicrobial activities of the treated samples were tested after 15 laundering cycles. The whiteness and wrinkle recovery angle of the treated fabric were also examined. The glutaraldehyde treatment was superior to CA treatment in terms of prolonged antimicrobial activity of the samples after successive laundering. Also, the treated samples with glutaraldehyde showed a higher wrinkle recovery angle with excessive deterioration in whiteness when compared with CA and BTCA. The treated samples with CA and BTCA show good antimicrobial activity after successive laundering and improved wrinkle recovery angle. However, BTCA indicates a higher durability in comparison with CA and same durability after repeated laundering with glutaraldehyde. This can be achieved without yellowing and unpleasant odor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 178–185, 2007

Solution of a partial differential equation subject to temperature overspecification by He's homotopy perturbation method

Abstract: In this work, the solution of an inverse problem concerning a diffusion equation with source control parameters is presented. The homotopy perturbation method is employed to solve this equation. This method changes a difficult problem into a simple problem which can be easily solved. In this procedure, according to the homotopy technique, a homotopy with an embedding parameter p[0,1] is constructed, and this parameter is considered a 'small parameter', so the method is called the homotopy perturbation method, which can take full advantage of the traditional perturbation method and homotopy technique. The approximations obtained by the proposed method are uniformly valid not only for small parameters, but also for very large parameters. The fact that this technique, in contrast to the traditional perturbation methods, does not require a small parameter in the system, leads to wide applications in nonlinear equations.

A numerical method for KdV equation using collocation and radial basis functions

Abstract: Recently, there has been an increasing interest in the study of initial boundary value problems for Korteweg–de Vries (KdV) equations. In this paper, we propose a numerical scheme to solve the third-order nonlinear KdV equation using collocation points and approximating the solution using multiquadric (MQ) radial basis function (RBF). The scheme works in a similar fashion as finite-difference methods. Numerical examples are given to confirm the good accuracy of the presented scheme.

Degumming of Persian silk with mixed proteolytic enzymes

Abstract: The feasibility of degumming Persian silk with alcalase, savinase, and mixtures of these enzymes with different alcalase/savinase weight ratios (0/1, 0.25/0.75, 0.5/0.5, 0.75/0.25, and 1/0 g/L) was investigated. The results were compared with those of soap degumming, which is a common silk degumming process. The effectiveness of parameters such as the treatment time, concentration of enzymes, and liquid ratio on degumming was studied. The enzymatic degumming process was performed at 55°C with an operation time of approximately 30 min, whereas the soap degumming process was carried out around the boiling point in 120 min. The evaluation of the data was carried out through the measurement of the weight loss, strength, and elongation of the samples. The optimum amount of sericin removed was 21.52 wt % for alcalase in 30 min, 20.08 wt % for savinase in 60 min, and 22.58 wt % for soap in 120 min. Also, the enzymatic treatment improved properties of the silk yarn such as the strength (33.76 cN/tex for alcalase and 32.03 cN/tex for savinase) and elongation (20.08% for alcalase and 18.42% for savinase). The obtained values were better than the strength (29.90 cN/tex) and elongation (18.59%) from the soap degumming method. Through the use of an enzyme mixture (0.5/0.5 g/L), good weight loss (22.43%), strength (33.22 cN/tex), and elongation (17.74%) were achieved in 30 min. Scanning electron micrographs confirmed and supported the observed data. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

A Morphological-Based License Plate Location

Abstract: License plate location is an important phase in vehicle license plate recognition for intelligent transport systems. This paper presents a robust and real time method of license plate location. The proposed algorithm consists of some stages. In the first stage, we extract vertical edges of the input image using Sobel mask. In the next stage, histogram analysis is used for finding the candidate regions of license plate. Candidate regions are also verified by defined compact factor. In the last stage, we locate the license plate exactly with some morphological operators. Experiments have been conducted for this algorithm. 400 images taken from various scenes were employed, including diverse angles, different lightening conditions. The algorithm can quickly and correctly detect the region of license plate. The license plate detecting rate of success is 83.50%.