Sharif Digital Repository

In the present thesis, the effect of external magnetic fields on two-flavor Color Superconductive (2SC) phase, as one of the phases in the QCD phase diagram, is studied. To do this, an effective two-flavor Nambu-Jona Lasinio Lagrangian is used, which consists of two mass gaps, s = ?¯qq and ? = ? . The nonzero values of chiral and color mass these gaps induce spontaneous chiral and color symmetry breaking, and consequently two different phases. There is also a third phase, the normal phase, where s = ? = 0. We calculate the transition curves and the critical points in terms of three intensive quantities, the temperature, the chemical potential and the external magnetic field. We study, in... 

Let G be a graph. A twin edge k-coloring of G is a proper edge coloring of G with the elements of Z_k so that for every vertex u and v of G we have s(u)≠s(v), where s(u) is the sum of all colors of the edges incident with u. The minimum k for which G has a twin edge k-coloring is called twin chromatic index of G and denoted by χ_t^' (G). In this thesis we find the chromatic index of paths, cycles, complete graphs, complete bipartite graphs and some complete tripartite graphs. In 2014 it was conjectured that if G is a connected graph with at least 3 vertices and maximum degree Δ(G), then χ_t^' (G)≤Δ(G)+3  

Content Based Image Retrieval (CBIR) is a research area in computer vision. This area comprises of two main steps, low level feature extraction such as color, texture and shape extraction and also similarity measures for comparison of images. The challenge in this system is the existence semantic gap between the low level visual features and the high level image semantics. The aim of research in this field is to reduce this semantic gap. In this study the images are divided into regions using Meanshift method, for color segmentation and then moments of each region as color feature are calculated. Also for extracting texture the images are divided into regions using Jseg method, and then... 

In recent years, there has been a growing research interest in segmenting skin regions in color images. Skin segmentation aims at locating skin regions in an unconstrained input image. Skin detection is considered as an important preprocess in many applications such as face detection, face tracking, and filtering of objectionable web images. The most attractive properties of skin detection include low computational cost, increase of the total processing speed, and being invariance against rotation, scale, partial occlusion, and pose change. Because of the diversity of various image processing tasks, there exists no optimum method that can perform properly for all applications. Most of the... 

Sequential coloring of graphs was first introduced by Tucker in [Tucker (1983)] to study perfect graphs, and was subsequently studied from a number of different perspectives, such as its connections to uniquely colorable graphs. In this thesis we begin by introducing the version of sequential coloring of graphs defined by [Daneshgar and Ebrahimi (2008)], and after surveying their results concerning the defining sets of sequential coloring of graphs, and also surveying the results obtained by [Daneshgar, Rahimi and Taati (2010)] and [Daneshgar, Hajiabolhassan and Taati (2010)] regarding the simulation of functions using sequential coloring of graphs, we turn to the reduction systems that can... 

The treatment of water effluent from alcohol industries is among the most challenging industrial wastewater treatments. The challenge mainly arises from the high capacity of organic compounds allowing the growth of microorganisms and pollutants. Brown color of the wastewater also contributes to this phenomenon; it absorbs more sunlight which then reduces the oxygenation of water and thus adversely affecting the aquatic life. Moreover, the acidity of the wastewater decreases the pH level of agricultural soils, so its quality Thus, distillery wastewater, without any treatment can pose a serious threat to the environment. In our study, we investigate the decolorization of molasses wastewater... 

In this thesis, we study the coloring problem in interval graphs within a relaxed variant of the online model. In this variant, vertices are introduced one by one and must be colored immediately, without any knowledge of the remaining portion of the graph. Our goal is to minimize the number of colors used, while ensuring that adjacent vertices always have distinct colors. This relaxed variant deviates from the traditional online model by allowing a limited number of previously colored vertices to be recolored. The number of recolorings per update is called the recourse budget. Our primary contribution is the design of three algorithms: one for unit interval graphs and two for general... 

The ability of measuring colors of objects, independent of light source illumination, is called color constancy which is an important field in machine vision and image processing. In this thesis, we propose five new combinantional ways in color constansy fields. The first two proposed methods use neural networks to combining basic methods. The third and forth proposed methods use fuzzy measures and integrals for combining color constancy methods. And finally fifth method combines methods with indoor outdoor classification this method has the best result (3.01 median angular error) in proposed methods and past methods in color constancy fields. It is shown in this article that the proposed... 

In the general case of minimum color-spanning tree which is one of the color-spanning set problems, given a weighted graph with n vertices of k different colors, the goal is to find a subtree of minimum weight such that vertices of this subtree include all the colors in the graph. In the planar case, the input is a complete graph with n colored vertices on the plane and the weight of each edge is the Euclidean distance between its corresponding vertices. In this thesis we consider the problem of minimum color-spanning tree. To this end, first we present various color-spanning set problems and some other related problems like Steiner tree and we study the previous work on these problems. Then... 

There are several methods for measuring thin film thickness, however, for the analysis of liquid film motors [1] we need a method which is capable of measuring the thickness using a single image of the film. In this work, we use the colors that appear on thin films, such as soup bubbles, which is a result of light interference to calculate the thickness of the layer  

In the year 1997, at 16th British Combinatorial Conference Cameron introduced a new concept called 2-simultaneous coloring. He used this concept to reformulate a conjecture of Keedwell on the existence of critical partial Latin squares of a given type. After that, other people studied special cases of this conjecture. They also studied the relation between this conjecture and other well-known conjectures in Combinatorics, such as Cycle Double Cover Conjecture (CDC). Finally, in 2004 the general case of this conjecture was proven. In first two sections, in addition to defining some fundamental concepts, we represent the relation between Latin trade and 2-simultaneous coloring. Afterwards, by... 

The visibility is one of the most important problems in computational geometry. Two points are said to be visible to each other, if the line segment that joins them does not intersect any obstacles. The art gallery problem is a well-studied visibility problem in computational geometry. It originates from a real-world problem of guarding an art gallery with the minimum number of guards who together can observe the whole gallery. In many of applications, the “guards” are “landmarks” deployed in an environment to help provide navigation and localization service to mobile robots. The mobile device communicates with these landmarks through wireless, or other “line-of-sight” signaling... 

In this thesis, we consider the problem of online conflict-free coloring for regions. First, we analyze online variant of the conflict-free coloring of intervals on the line, where each newly inserted interval must be assigned a color upon insertion such that the coloring remains conflict-free, i.e. for every point p in the union of the current intervals, there must be an interval I with a unique color among all intervals covering p. we present deterministic algorithm for achieving this goal which uses O(log^3⁡n) color. Next, we consider the online conflict-free coloring of nearly-equal axis-parallel rectangles in the plane and present a deterministic algorithms which uses O(log^12⁡n)... 

Azo dyes that are the most common dyes in textile industries, are toxic and stable complex compounds. Release of this dyes in environment disturb the ecosystem and endanger human health. So selection of an appropriate method for treatment of them is a sensitive work. photocatalytic degradation is one of the best promising methods because of its perfect mineralization, middle condition and lack of creating the secondary pollutant. In this research CuO/CNT nanocomposite was synthesized and used as a photocatalyst. The surface features of CuO/CNT were surveyed by using Fourier transform infrared(FTIR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM). Photocatalytic efficiency of... 

Removing pollutants of water and, in general, wastewater treatment is one of the most important issues in the world. In this research, we synthesized a nanophotocatalyst based on znic-iron in the form of a magnetic core-shell Fe3O4@ZIF-8, and used to degrade the malachite green toxic color of wastewater. SEM, XRD and FT-IR analyzes have been taken and analyzed fore all three core, shell and core-shell composite catalysts.Due to the band gap of core-shell nanocomposite and the performance of the malachite green dye, a photocatalytic process under the visible light was obtained, which at an optimum amount of photocatalyst 0.003g, we reach 99.2% dye degradation at the 30ppm concentration. This... 

The present work is based on the, synthesis and investigation of photocatalytic activity of TiO2, TiO2/MWCNT, ZnO and ZnO/MWCNT nanostructures. The nanostructures were prepared using multi-walled carbonnanotubes (MWCNT) as templates.The SEM images of TiO2 and ZnO nanoparticles and TiO2/MWCNT andZnO/MWCNT showed that nanosize TiO2 and ZnO particles homogeneously and densely supported on the surfaces of multiwall carbon nanotubes the photocatalytic activity of the TiO2, TiO2 /MWCNT, ZnO and ZnO/MWCNT was examined by the degradation of Basic Blue 41(BB41) under UV and Vis lights. The optimum conditions for degradation of BB41 on TiO2 where found to be: calcination temperature (450 °C), dye... 

In content based image retrieval, low level features are used to find similar image. To do this, many system has been proposed by other people, in which in many of them, combination of features in the same time are used as a step of retrieval to increase accuracy. Feature combination are divied in two category: vector based and weight based which in weight based approach, features can get different weight, based on their importance and role in retrieval accuracy. Each image contain different partition, which some of them like background, base on their lower discrimintivity power, have lower importance. Based on our study, some image have powerfull color features and some of them have... 

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... 

The conflict-free coloring is one of the computational geometry problems that has received attention in the last two decades. The root of this problem comes from the frequency allocation problem to telecommunications antennas, where we have several telecommunication antennas in two-dimensional space aiming to assign to each of them a frequency so that every point on the plane, which is at least inside one of the antenna ranges, stays in a range with a frequency different from the other antennas containing point.One of the generalizations of this problem is the k-strong case, where we have n regions (equivalent to the circular region of the antennas) that we want to color so that for each... 

Meeting timing constraints is crucial for the correct behavior of embedded systems in modern vehicles. In the automotive domain, TADL2 Timing constraints are widely used and accepted standards for repetitive and critical timing requirements. However, ensuring these constraints in modern automotive systems, which encompass over 150 Electronic Control Units (ECUs), is challenging due to the increased complexity of automotive systems. Previous work proposed formal frameworks for specifying and verifying timing constraints, mostly based on timed automata, Time(d) Petri Nets, and TCTL logic for specification, which are the most prominent formalisms in the timed system's domain. They used UPPAAL...