Sharif Digital Repository

In recent years, stochastic-flow networks (SFNs) have been extensively applied to many problems such as distribution, power transmission, and telecommunication. In quality management and decision making, an important task is to design some performance indices in order to measure the performance of an SFN. The system reliability and unreliability are such two common performance indices.Hitherto, several research works have been conducted for evaluating these two performance indices.One approach for evaluating the reliability of SFNs is determining all the upper or lower boundary points (respectively, UBPs or LBPs).Here, we study four problems to determine: (1) all the UBPs in a two-terminal... 

Object recognition is a field of image processing with the purpose of object detection and determining its pose. There was a wide research of object recognition using 2d information. These methods are less efficient due to their sensitivity to view and scale. Today with development of 3d technology, 3d reconstruction of objects has been eased, thus there is a new trend of 3d methods. 3d object recognition uses 3d data and model to recognize objects more efficiently in different views and in occlusion and clutter. The related works are classified in three category of view-based, feature matching, and classification. In this research we attempted to improve one of the best feature matching... 

Regarding to the emergence of quantum computers and advances in the large scale implementation of them, exploiting hard problems of coding theory is of great importance.This family of problems, like those of lattices, has an acceptable resistance against classic and quantum attacks. Thus, they can be replaced with hard problems in number theory and algebra. Increasing dominance of cyberspace made us highly dependent to it. Consequently, preparing tools and methods to mitigate future threats is necessary. Digital signatures constitute an important family of cryptographic primitives. Code-based digital signatures are mostly suffering from two main drawbacks: large public key and long time of... 

Designing and evaluating the segmented production structures of the production system due to the variety of production systems is one of the important issues that have been considered in recent decade. In this research, the paradigm of designing a segmented production system has been studied to increase the adaptation of the organizational structure of production systems to changing and diverse behavior of the market as well as to increase the responsiveness to demand in the organization. The segmented production system provides production units to small, flexible and decentralized production units. The segmentation process used in this research uses an axiomatic design structure. The... 

Software development process is a base ground for all software activities and ensures all aspects of the software. No quality is guaranteed without a definite process. Model-Driven Software Development process proposes an industrial method for software companies to produce the required software through model(s) and tools. On the other hand, Software Product Line imposes a set of frameworks and principles. As a result a tangible decrement of development time and cost along with an increment of quality is achieved. Mixing both processes creates a stronger industrial process in order to decrease the development time and cost. In this thesis, through a survey on both of the processes and related... 

Gold Coin Futures Market by contract delivery month of Dey, in 1387 as part of the capital market in Iran Mercantile Exchange started its activities. Each transaction in this market includes ten coins all gold (tamam bahar). Nowadays We have three symbols on each of the next three months are traded in an active market. In this market, any natural or legal person giving the guarantee fund with any of the agencies approved by the Stock Organization and in the terms of seller or buyer begin their trading. For transactions in order to succeed, we need to predict the rise or fall of prices to be a buyer in the rises and be seller in the falls. With considering the performance of Neural Networks... 

In this research, the effects of natural and artificial aging heat treatments on the mechanical and wear behavior of an aluminum alloy from the 7xxx series have been investigated. The study commenced with annealing of the received samples, which were subsequently divided into four categories. One of these categories was placed in a freezer as annealed samples, while the other two underwent artificial aging heat treatments at temperatures of 180 and 210 degrees Celsius. The final category naturally aged over time. As a result, different structures with varied distributions and morphologies of precipitates were formed, and the mechanical properties, mechanisms, and wear resistance of the...