Sharif Digital Repository

We have studied making and characterization of gasochromic thin films that are used as gas sensors. Gasochromic films consist of an electronchromic layer and a catalyst layer. Addition of palladium to the surface , increased the sensitivity and decreased the working temperature. The used electrochromic layer was tungsten oxide. WO3 films were fabricated by (PLD) method. The substrates were slide glasses. Structure, morphology and composite of tungsten oxide and optical property of films depend on condition of deposition. The pressure of oxygen gas in chamber and temperature of substrate are two factors that can affect in deposition. We can make layers with different morphology by variation... 

In this thesis, arranged by [6], the multiplier method is used to solve the network problems with nonlinear constraints and the Newton-like methods are used for updating the required parameters. This method, recently proposed in the literature, is based on solving a sequence of nonlinear optimization subproblems, dependent on the main problem, such that sequence of solutions of these problems converge to the solution of the main problem. In fact, to obtain an acceptable approximation of the main solution, it is needed to solve just a finite number of nonlinear subproblems. The main idea of the multiplier methods is based on eliminating some constraints and adding a penalty term to the... 

In this thesis, we want to present methods that are able to solve the assignment tasks problem in a heterogeneous computing system. These methods are two hybrid methods that are constructed by composing Hopefield Neural Networks with Genetic Algorithms and the Simulated Annealing. First, we solve the relaxed problem by applying Genetic Algorithms and the Simulated Annealing and we compare the results of these ways with other traditional methods. Then, we solve the constrained problem with mentioned hybrid methods. The definition of the problem is as following: Consider a distributed computing system which is comprised of set of processors with different speeds but the same structure. We want... 

DNA microarrays consist of DNA microscopic points that are attached to a solid surface such as glass, plastic or silicon chip and formed as an array. The fixed pieces of DNA are considered as searchers. In an experiment, we can use thousands of searchers. Therefore, any microarray consists of the same number of genetic tests as the experiment performed on all of them in parallel. Whit this ability, arrays have speeded up the biological investigations. Microarray technology can be seen as a continued development of southern blotting. However, the most important stage in this technology, analysis of data, requires reliable bioinformatics tools achieving high reliabilities. Infectious diseases,... 

The field of digital image processing refers to processing digital images by means of a digital computer. One of the principal applications used in digital image processing is image compression. Image compression is the problem of reducing the amount of data required to represent a digital image. The basis of the reduction process is the removal of redundant data. One of the other principal applications of image processing is noise reduction (filtering) of images corrupted with additive noise. Filtering techniques are oriented toward modeling the degradation and applying the inverse process in order to recover the original image. Image watermarking is another application of image processing.... 

During the last few years, utilization of distributed generation (DG) in power systems has been widely increased. This trend has magnified studying the effects and impacts of DG on such systems. One of the benefits of DGs in a power system is loss reduction. If determining DG size and place is done properly, the loss of the network can be minimized. Another way of reducing loss in distribution network is by reconfiguring the network. During the reconfiguration, constraints like being radial, avoiding load isolation as well as voltage/current limitations must be taken into consideration. Taking these constraints into account makes reconfiguration an optimization problem. In this project, the... 

Conjugate gradient methods are appealing for large scale nonlinear optimization problems, because they avoid the storage of matrices. Recently, a new conjugacy condition proposed by Dai and Liao, considers an inexact line search scheme that reduces to the old one if the line search is exact. Based on this condition, a new conjugate gradient method was proposed that has fast convergence. Later, Yabe and Takano, based on new conjugacy condition and modified secant condition, proposed another conjugate gradient method. This method takes both the available gradient and function value information and achieves a high-order accuracy in approximating the second-order curvature of the objective... 

Bezier curves are among important curves which are broadly used in different fields such as computer graphic, vector graphic and animation. Among softwares in which these curves are used nowadays are: Adobe, Inkscape, GIMP, Adobe Photoshop, and Illustrator. An important concept in drawing the Bezier curves is to plot these curveswith fewer numbers of control points (low degree). Many algorithms have been introduced to reduce the degree of bezier curves. Here we first describe Bezier curves and their properties. Our main concern here is implementation of a new algorithm for multi-degree reduction of Bezier curves which are constrainted. The algorithm has recently been proposed byWozny and... 

A new method, recently introduced in the literature, is discussed for solving equality constrained nonlinear optimization problems. This method does not use a penalty or a barrier function, or a filter, and yet its global convergence to first-order stationary points can be proved. The method uses different trust regions to cope with the nonlinearities of the objective function and the constraints, and admits inexact SQP steps not lying exactly in the nullspace of the local Jacobian. We implement the method in MATLAb 7.7 software environment and test the resulting program on a collection of CUTEr problems. The numerical results are promising and confirm the global convergence of the method  

We propose practical ABS approaches for solving linear Diophantine systems and sparse null space basis problem. For solving linear Diophantine systems, we propose an approach for generalizing Rosser’s algorithm and present two algorithms for solving systems of linear Diophantine equations. Then, we show that the generalized approach provides us with a new formulation of the LDSSBR of Chou and Collins and a more efficient implementation of Rosser’s approach. We present a new class of integer extended ABS algorithms for solving linear Diophantine systems. The proposed class contains the integer ABS (the so–called EMAS) and our proposed MEMAS algorithms and the generalized Rosser’s algorithm as... 

Physical and chemical properties of tungsten oxide thin films change reversibly while exposure to hydrogen gas. This property is called gasochromic. To enhance optical properties of such films, nanostructured, amorphous and porous thin films of (WO3)1-x(MeO)x (MeO= TiO2, MoO3, NiO; x=0.09, 0.17, 0.23, 0.29, 0.33) were fabricated by Pulsed Laser Deposition. Molar percentage of Me/W (Me= Ti, Mo and Ni) was changed in films with respect to targets; for Ti and Ni always a reduction, but for Mo an enhancement for low percentages was observed. The reason is the existence of thermal ablation mechanism during deposition, in the other word is different vapor pressure effect. An increment in x for... 

In the modern world, steganography is an image processing technique, revealing to be a suitable process for information hiding. In most cases, steganography has shown to be more effective than cryptography techniques. Recently, there have been attempts to improve the stego-image quality and hiding capacity by introducing new methods. Here, we inspect the advantages and disadvantages of some new steganography methods for digital images. The implemented methods are color and grayscale image steganography with OPVSP algorithm, BRL and GRL methods, and the simple LSB method with OPAP algorithm. Here, we compare the implementation results of these methods using MATLAB 7.4.0, with other common... 

Here, we first ivestigate some available nonsmooth algorithms indentilying their drawbacks, and then provide some guidelines to avert these drawbacks. We divide the algorithms to two main classes, first order and second order. The main drawback of the second order class of algorithm is that there does not exist any suitable method to approximate the generalized second order derivative. To solve this problem, we construct a uniform approximation for the generalized Hessian matrix of an SC1 function. Using the discrete gradient and the extended second order derivative, we define the discrete Hessian matrix. We construct a sequence of sets, where each set is composed of discrete Hessian... 

In software testing, it is often desirable to find test inputs that exercise specific program features. Good testing means uncovering as many faults as possible with a potent set of tests. Thus, a test series that has the potential to uncover many faults is better than one that can only uncover a few. To find these inputs by hand is extremely time-consuming, especially when the software is complex. Therefore, many attempts have been made to automate the process. There are three major methods to generate software test data: Random test data generation, Symbolic test data generation and Dynamic test data generation. Dynamic test data generation, such as those using genetic algorithms, is... 

We deal with primal-dual interior point methods for solving the linear programming problem.Taken from recent literature on interior point methods, we discuss a short-step and a long-step path-following primal-dual method and show how to have polynomial-time bounds for both methods. The iteration bounds are for the short-step variant and for the long-step variant. In the analysis of both variants, a new proximity measure is used, which is closely related to the Euclidean norm of the scaled search direction vectors. The analysis of the long-step method depends strongly on the fact that the usual search directions form a descent direction for the so-called primal-dual logarithmic barrier... 

The present work emphasizes on hydrogen resistance- sensing properties of WO3 films prepared by Sol-gel routs. The sol-gel is a simple and low cost rout which makes film with high homogeneity and low processing temperature .To improve Hydrogen sensing we modified WO3 films with Pd catalysts by Sol-gel and Electroless methods. AFM , EDX, SEM , XPS , XRD , were applied to analyze structure, morphology and Chemical composition of the fabricated thin films. We measured resistance sensing behavior of prepared films in exposure to different concentration of Hydrogen. All the films were tested under the same conditions. We measured resistance sensing in exposure to concentration below 10000 ppm... 

Over the last few years, much effort has been directed into developing new materials that have specific antibacterial and antifungal activities that can be used to fight infections and to create sterile conditions. Nanotechnology could become very important in this research field, providing the tools needed to synthesize copper-containing nanomaterials showing an enhanced bioactivity. This nanomaterials have been used in a number of textiles, plastics and ceramics coming on the market in recent years. In this thesis, we synthesized copper-polymer nanocomposites by blending of pre-formed copper nanoparticle into pre-synthesized polymer. We used a new method of nanoparticle preparation by... 

In recent decades fuzzy linear programming and possiblistic linear programming models have been considered as strong tools for modeling uncertainty of problems. Here, after describing the possibility theory and considering the fuzzy relations with respect to possiblistic programming, we consider some models of fuzzy linear programming and its possiblistic model. Then, some of stochastic linear programming are discussed. After explanning the portfolio selection problem, we analyz and compare the numerical results of these two kinds of linear programming approaches. Finally using MATLAB software enviroment, the algorithms are implemented and tested  

Here, the properties of separability of linkages are studied. In general, a linkage is a simple polygonal chain embedded in 3-space with disjoint, straight-line edges, which are fixed-length bars. The internal vertices are called joints. If the two end points are connected then the linkage is a closed linkage, otherwise it is an open linkage. By imposing restrictions on the way the bars in joints can move, three kinds of linkages as rigid, revolute and flexible can be introduced. A motion in a linkage is the motion of its vertices that preserves the length of the bars, and adheres the restrictions on joints. A collection of linkages are said to be separatable if for any distance d, there is...