Sharif Digital Repository

Peer-to-Peer networks are invented to enable participants (peers) to share their resources and find and use the shared resources of the others. So the main issue is the mechanism of finding granted resources of the other peers. In Peer-to-Peer networks, there is no central server to index shared resources of the peers. So peers should collaborate to provide a fully distributed mechanism for searching resources. Considering the huge size of peer-to-peer systems, it is apparent that efficiency of the search mechanism is very critical. In this thesis, to have efficient seach in Peer-to-Peer networks, we propose two approaches. Then based on these approaches, we propose the third approach to... 

The Use of peer-to-peer architectures instead of traditional client-server architecture can be beneficial in many aspects such as increasing scalability of the systems, enhancing fault tolerance in critical situations, extending the system resources and various other advantages. Nowadays, many applications are based on peer-to-peer architectures and as a result, a large portion of the internet traffic is produced by these applications. This has been a motivation to many researchers to focus on reducing the amount of this traffic while satisfying the content distribution demands. One of the main problems that can result in generating large amount of traffic and also long response times for... 

In today’s competitive world، web services have become more and more prevalent and their efficient discovery and composition in order to create novel functionalities is essential for variety of applications. Due to the large number of available services، the discovery of services is a difficult and time consuming task. Existing approaches in web services discovery and composition attempt to use simple web services while ignoring the use of once composed services. Reusing frequently used composite services can considerably increase performance of the entire system. Moreover، the advent of semantic web، as an effective solution of representing information interpretable by machines and none... 

Today, peer to peer networks have become quite popular due to their ability to easy access to shared resources regardless of their location in World. In these systems files are stored at the end user machines which named peer, rather than at a central server, in contrast to the traditional client-server systems, files are transferred directly between peers. sending and receiving those data, occupy a large amount of the internet bandwidth. So, by improving the efficiency of these networks, the total efficiency of the internet will improved. These systems are usually constructed on the other networks such as TCP/IP as an underlay or physical networks. Despite of structure of peer to peer... 

Nowadays, the essentiality of appropriate modeling languages has become evident, and with the introduction of new concepts such as domain-specific languages, the need for systematic research on designing and engineering new modeling languages has increased significantly. Several modeling languages have been developed and employed over the years, but the area of modeling languages still suffers from the lack of a proper framework: There is a strong need for an engineering framework that specifies the detailed steps of language development, the input and output artifacts of each step, the techniques applicable to each step, and quantifiable methods for quality measurement. From a unified point... 

In the pas few years, the use of web-based education systems have grown exponentially spurred by the fact that neither students nor teachers are bound to a specific location and that this form of computer-based education is virtually independent of any specific hardware platforms. These systems can offer a great variety of channels and workspaces to facilitate information sharing and communication between participants in a course, let educators distribute information to students, produce content material, prepare assignments and tests, engage in discussions, manage distance classes and enable collaborative learning with virtual classroom sessions, forums, chats, file storage areas, news... 

Software Product Line is known as a process of developing family of the software together. The methods of building a software product line is trying to capture commonality and variety of this family of software and form a product line based on them. Commonality of this family of the software allows us reuse in every aspect of the development of software. Nowadays, software architecture as a one of the most important aspect of software engineering, plays major role in specifying the tasks and clearing the relationship between people. It can divide large and complex system to some sub-system and overcome complexity of the system. Software architecture forms a basis for communication among... 

Due to the increase in size and complexity of software systems, choosing suitable software architecture is a fundamental issue. One of the most effective ways for designing and valuating software architectures is to adopt architectural styles. An architectural style is an approach for reaping the benefits of similarities that exist between various architectures. Adoption of architectural styles in the design process of a software system assures the employment of strength points of specifications that belong to each architectural style. However, selecting a suitable architectural style depends on different criteria. Therefore it makes the ... 

Business Processes are a set of activities which is designed for produce specific output for specific customer or market. Nowadays business processes have a significant role in organizations and they progress to mechanized business processes and transform them to executable workflows. Existence of complex domains with particular requirements from one hand and scale of business projects on the other hand, make existing business processes, which only consider structure and flow of work, are not enough for fulfillment of organizational requirements. By provision of semantics into business processes, which Semantic Web technologies is used in them, business processes become more flexible and... 

internet can be seen as a revolution in human lives whose influences are obvious to everyone and nowadays it’s impossible to consider a world without it. most of people’s means of internet is the world wide web and this shows the importance of web. Web services as a modular and independent applications which can do most of our works through the web, improves its importance. This applications can be located, distributed and called through the web, most of organization’s activity which we can’t imagine internet without it. Semantic web can be considered as a new web architecture which integrates web content with semantics which can be understood by computers. the main motivation for semantic ... 

Due to the advances in wireless communications and electronics over the last few years, the development of networks of low-cost, low-power, and multifunctional sensors has received increasing attention. Most important constraints of this network are energy and bandwidth. Data aggregation is one of the effective approaches for reducing energy consumption in wireless sensor networks. Recent research on data collection reveals that, rather than reporting data through long, multi-hop and error-prone routes to a static sink using tree or cluster network structure, allowing and leveraging sink mobility is more promising for energy efficient data gathering. In this work we proposed an effective... 

Our surrounding environment has valuable information about our life. We live in technological societies where we are leaving digital footprints in, continuously. Growing development and popularity of mobile phones, has turned them into the most important global sensors. Mobile phone tracking via GPS points is one of the data types which can be collected from these sensors and used for traffic monitoring, intelligence traffic control and travel time estimation.
In order to use these devices, we need to collect data, detect transportation mode and estimate travel time. By evaluation of previous works, we can feel the need to a comprehensive approach for detecting transportation mode of... 

The architecture of a software system, its elements and the way they interact is a valuable treasure for understanding the system. If architecture description of a system is not available, working on its extraction and reconstruction should be done. For a software with huge size and vast complexity, architecture extraction by hand and without any predefined method is nearly impossible. So, it is essential for software architecture extractor to use a framework and a well-defined process related to it, for extracting the software architecture. It can help him to use automated tools as much as possible in addition to havingauniquelogicalstructureforperformingthearchitectureextractionprocess. In... 

Study of real networks has become an important research task. Real networks appear in different domains such as social networks and biological networks. It is also possible to extract various networks from the set of scientific collaborations of published papers. In this project we investigate the analysis of citation network and co-authorship networks of scientific papers in order to find out a new method in citation recommendation of scientific papers. Presented method have some superior properties over existing citation recommendation systems like combining different fields for suggesting most relevant papers to user, in response of user’s input keywords. For presenting this method we... 

Considering the aggregation of software architecture design decisions, the decision on appropriate from, is important to the success of a software project. Hence, the software architects need reliable and accurate process for correct decision making which seeks to reduce risk and increase productivity. Furthermore, different stakeholders involved in the architectural design process and presence of cooperation between them for architecture decision making indicates the nature of collaborative activities related to architectural design. Effective collaboration among those involved in the design process not only will affect on the quality and accuracy of the architecture, but also accelerates... 

With the advent of software product lines as a practical approach in software engineering, research on this area has increased exponentially. In Software product lines a platform is presented onto which a product family can be created with ease. With the help of this platform each software in the product family can be produced with small modifications. Using this approach, cost and time of producing software decreases whilst at the same time increasing the overall software quality. Changes in standards, instability in business needs and variable requirements of various stakeholders will always cause evolution in a software product line. These change areas cannot always be predicted by... 

Nowadays, M&S is critical as a powerful tool for human to fight against cancer. Skin cancer is one of the most widespread cancers and melanoma would be the most dangerous kind of it. In cancerous micro-environment, cancer cells interact with vasculature, and compete with normal cells over nutrients. This plays a major role in tumor progression pattern and speed. In recent years, a few multiscale models have been developed considering these phenomena. Such a model provides a platform for future researches, especially in drug effects prediction. A reliable simulation must satisfy the constraints and facts in the real world as much as possible. M&S credibility assessment is a major concern to... 

Evolutionary algorithm is an important algorithm in software field. Today evolutionary algorithms are used in many applications such as Artificial Art, Automated Design, Bio-informatics, Communications, etc. Many articles has been published in this field. The Evaluation of this algorithms have two approaches, the quality of result and the runtime of the algorithm. In this thesis we proposed a new use of Social Networks in Genetic Algorithm, and we designed a parallel model of it on CUDA GPUs. The main idea was that we seen a good content spread in the social networks very easy and fast. We used this idea to improve genetic algorithm by creating a social network between people of a... 

The purpose of IT management and governance is to empower the alignment between IT and business in organizations. IT management and governance focuses on the optimal utilization of IT resources in order to support business processes, address the organization’s needs and meet the organization’s goals. Even though every IT governance framework emphasizes on a particular dimension of this extensive domain, the common nature of all these frameworks, which is IT and business alignment, would make the efforts put into integrating them desirable and reasonable. Implementing different IT governance frameworks in separate projects, not only results in redundant or inconsistent outputs and artifacts,... 

Proposing a comprehensive architecture for cloud federation with the aim of satisfying stakeholders the most, is one of the most challenging issues in this context. For an architecture to be comprehensive, requirements should be elicited thoroughly in early stages of architecture design. Since covering all requirements is a very complicated task, prioritization is considered to be a vital step which can help architects to focus on more important requirements in their design as well as to evaluate existing architectures. In this research, architecturally signifcant quality requirements of cloud federation for aggregated cloud architectures are studied and categorized. Moreover, elicited...