Sharif Digital Repository

There is much interest in the theoretical study of the structure of hypercubes because their structure has played an important role in the development of parallel processing and is still quite popular and influential.This thesis will begin with an introduction to hypercubes and some of their problems. Then we study the following concepts: Arboricity (The minimum number of edge-disjoint forests into which a graph can be decomposed), Galactic number (similar to arboricity but such that each component of each forest is a star), Silver coloring (Given a set I of maximal independent vertices, a silver coloring with respect to I is such that every v 2 I sees every other colors in its closed... 

Conflict-free coloring problem is one of the computational geometry problems that has been studied in the last two decades. The root of this problem comes from the frequency assignment to cellular networks problem. In that research, we have a cellular network containing several regions in two-dimensional plane and we want to assign a frequency to each of the regions so that if we look at any intersection of them, there is a region with a unique color compared to other regions of that intersection. In other words, a person’s cellular phone in the range of some regions (in the intersection of them) would be able to connect to one antenna with a unique frequency and function properly. This... 

Dye sensitized solar cells are one of the cheap and available technologies that have attracted the attention of many researchers. Many factors such as morphology, microstructure, phase composition and the arrangement of photoanode electrode layers have an effect on the photovoltaic properties of DSSCs. Different approaches have been used to improve the efficiency of this type of cells. Among these approaches, we can mention the use of a mixture of different phases of titanium dioxide and the use of perovskite titanate structures as photoanodes. In the current study, the performance of nickel titanate on light absorption and electron-hole separation in titanium dioxide-based dye-sensitized...