Sharif Digital Repository

Medical images contain information about vital organic tissues inside of the human body and are widely used for diagnoses of diseases or for surgical purposes. Image Reconstruction is essential for medical imaging for medical systems like suppression of noise or de-blurring from projections in order to have images with better quality and contrast. Due to the vital role of image reconstruction in medical sciences the corresponding algorithms with better efficiency and higher speed is preferable. Most algorithms in the field of image reconstruction are operated in frequency domain such as the filtered back projection which is a popular algorithm for the reconstruction of the medical images. In... 

Dealing with different supply chain risks and how firms should prepare against them has become an important issue in real world application. In this paper, we propose a periodic model to fortify supply chain structure against disruption by remanufacturing different types of returned products at first priority and manufacturing raw materials at second priority only if it is necessary. Additionally, our approach to model disruption is that there are two kinds of facilities for manufacturing/ remanufacturing centers. The first one is reliable and the second one is unreliable. Therefore, in this paper, we formulate and solve a reliable discrete dynamic linear programming with different types of... 

Nowadays active Millimeter Wave Imaging Systems are used in verity of medical and security applications. This widespread application re- sults from the intrinsic characteristic of electromagnetic waves in this rang of frequency that can penetrate through interior body structures and clothing with- out bringing harmful ionizing efects to the body. Millimeterwave systems can be very high resolution due to the relatively short wavelength. The current state-of-the-art in active millimeter-wave imaging systems use a set of transmit/receive antennae. The transmitter antennae illuminated the intended person with millimeter waves while the back scattered signal is recorded by the receiver antennae.... 

Visibility graph is a graph that comprises information about visibility of a set of objects in 2 or 3-dimensional space. By constructing this graph with respect to conditions of environment one can answer questions like minimum Euclidean distance. Inverse of this procedure is required too; i.e. knowing geometrical structure of objects and information about their visibility we want to guess their location in space and, as the saying goes, reconstruct the environment. For example some methods to reconstruct specific polygons knowing which vertices each vertex sees is proposed. In this dissertation we try to reconstruct a 2-dimensional environment that only has two x-monotone paths (chains)  

For a simple polygon in the plane, the visibility graph is a graph whose vertices are the vertices of the polygon and there is an edge between two vertices if and only if their corresponding vertices see each other in the polygon. Two points of the polygon see each other if the line segment connecting them lies completely inside (or on the boundary of) the polygon. Although computing the visibility graph of a polygon has been solved efficiently, its reverse problem after three decades is still an open problem. The reverse problem is known as recognition and reconstruction visibility graphs. Recognizing visibility graphs is to determine the necessary and sufficient conditions on a graph to be... 

Preservation of historical monuments is a very important issue for future generations. The importance of this issue is doubled when we know that most of these buildings are traditionally built and do not have a single structure to withstand seismic loads. One of such buildings in our country is Bam Citadel, which was completely destroyed as the oldest brick building in the world during the 2003 Bam earthquake.In this project, we will try to find a model that can determine the structural behavior of the historical dome of Soltanieh for engineers in a case study. This building is a brick dome with a height of 48.5 meters and a diameter of 24.4 meters from the seventh century , which is unique... 

Nowadays population growth, people housing demand and urbanization tendency has increased the land and house prices. So the constructers tend to build apartments. Time consuming and heavy costs of building and renovation has made the owners to rebuild the damages of their houses in case of an accident. Time and cost are the main factors in construction which includes rebuilding. Buildings and especially apartments renovation is expensive and prolonged. So the rebuilding tendency has been noted more than ever. In this study it has been tried to control costs and time by efficient management to save the rebuilding time and money. Two kinds of questionnaire has been applied to study different... 

In this study, the reconstruction of the neutron noise source in the core of the VVER-1000 reactor was carried out using fuzzy neural network and parallel processing of parallel process circuit design. The noise of power reactors is derived from neutron fluctuations. Which are affected by fluctuations in reactor characteristics. These oscillations can be caused by the displacement of the elements forming the core or due to changes in temperature or density and so on. It is clear that any change in the elements of a reactor will make itself a change in the corresponding to cross-section of material. These changes called as pertubation. In this project, by using neuro-fuzzy network...