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... 

An ontology is a formal description of a domain by definition a set of concepts and the relationships between those concepts. Ontologies defined by different applications usually describe their domains in different terminologies,even when they cover the same domain. Thus, we need to resolve the semantic heterogeneities problem and align terms in different ontologies. Ontology alignment plays the central role in these areas to identify correspondences among elements of two or more ontologies. It should be noted that,finding an optimize mapping between two ontologies with respect to search space is an NP-hard [6] problem.
In This thesis we focused on large ontologies and alignment among... 

Ontology alignment is a process for selection of a good mapping between entities of two (or more) ontologies. It can be viewed as a two phase process of: 1) Find the similarity of each pair of entities from two ontologies, and 2) Extraction of an optimal or near optimal mapping. Many researches had been down in the first phase, but researches in the second phase are little. Mapping extraction approaches applied in ontology alignment use similarity matrix to extract mapping, and ontologies have not any role in mapping extraction phase. One of the most important components in ontology is its structure which can help us in alignment extraction.
In this thesis, an approach was proposed that... 

Web service plays an important role in software development. Since Web service can be used in small scale and large scale environments, many different entities may participate in each interaction. Regarding situation, a lot of information is available around these entities. This kind of information is called context. In some cases, context information is used to provide outputs which are called context-aware systems.
The main challenging issue in producing a context-aware system is context modeling and sharing. Semantic Web and its ontology languages are the most promising solution to context modeling. In pervasive computing many ontologies are proposed for this purpose, but little... 

Nowadays the importance of ontologies in various domains such as semantic web and NLP is obvious. Manually construction of ontologies is a time-consuming, costly and error prone. The non-manual building of ontologies approaches are divided to the expand approach and the merge approach, each has pros and cons. The expand approach is preferred upon the merge approach for languages with few lingual resources. The most important thing in the expand approach, which is building an ontology from another existing ontology, is making distinction between the different meanings of polysemous words. This activity is called word sense disambiguation(WSD). The existing approaches usually give attention to... 

There are six core concepts in the organization theories that theorists rely on. These six concepts are: environment , social structure, technology, culture, physical structure, power and control. the insights of theorists about each of these concepts lead to different theory in case, they argue. The enactment environment theory by carl weik, is one way of conceptualizing the organizational environment within the interpretive paradigm and offer an approach about the organization and its environment. The logic of the enactment environment theory based on the belief that organizational realities parallel to people interact and negotiate and make sense of their experiences are socially... 

Putting human commonsense knowledge into computers has always been a long standing dream of artificial intelligence (AI). Since the first days of its appearance, AI knowledge engineers were studying hard to get round this bottleneck. The cost of several tens of millions of dollars and times have been covered so that the computers could know about “objects falling, not rising.”,” running is faster than walking" And “death is the end of the life”. The large database was built, automated and semi-automated methods were introduced and volunteers’ efforts were utilized to achieve this, but an automated, high-throughput and low-noise method for commonsense collection still remains as the holy... 

The philosophers of social sciences, in addition to epistemological questions-the questions about our knowledge of the social world- implicitly or explicitly, consider ontological issues: the questions about the nature of social world (society, structures and relations, people and actions). In Critical Realism, ontology and epistemology are linked. It means that what it is awarded, it is crucial that knowledge can be gained from it. This school, with a critique of Positivism and Hermeneutics, tries to authenticate ontological arguments and by reconstruction of concepts like causality, necessity, structure and stratification reality, forms the realist ontology and offers a novel solution to... 

Software architecture patterns present solutions for facing with architecture problems and help to document the architectural design decisions. But diversity, complexity, and required expertise for selecting an appropriate pattern, would cause some difficulties in using architectural patterns. Using an ontology for registration of architectural patterns playing an efficient role in solving those problems. But the mentioned difficulties make the process of constructing the architectural patterns ontology more complicated. This thesis proposes an approach that would consider the construction of the architectural patterns ontology from four perspectives in order to overcome the ontology... 

As digital content grows rapidly due to the internet, user reviews about different topics such as product quality can be used as a rich source to check and analyze product quality and performance. Automatic methods are being widely used to extract these information because of the massive amount of available resources. Sentiment analysis is one of the important fields in natural language processing, which uses a combination of learning and rule-based methods to extract subjective information out of documents. Aspect based sentiment analysis deals with sentiment analysis based on each aspect of the product. It consists of two main steps: first, aspects should be extracted from the reviews and... 

Supply Chain is a complex system and its modeling generally results in complicated mathematical problems. Solving these problems, one should make assumptions that make solutions impractical. Knowledge-based frameworks such as ontology has been proposed for tackling this issue. In this thesis, with relying on a seven step ontology developing method, UML as development language and Rational Rose as development software environment, an application ontology for supply chain and its problems has been developed. Furthermore, with use of a Benzene, Toluene and Xylene supply chain as an instance, it has been shown qualitatively how to use the ontology in various supply chain problems. It is... 

Simulation of biological behaviors as the pre requirement for control and optimization, especially for recognition and treating diseases, requires studying involved reactions which may or may not be accessible. In the other side, finding the correct network structures and related mathematical expressions to simulate biological behaviors is a complicated problem due to multi aspect interactions among biological reactions, which imply an approach that integrate the knowledge coming from multiple discipline including biological concepts, mathematical modelling, bioinformatics and advanced programming. In this study we aim to analyze this problem using ontological inference to develop a... 

The environmental impact of process plants is one of the causes of the environmental disturbance in the world. Including the effects of these destructive impacts can be mentioned to the phenomena such as global warming, climate change, severe air pollution and water shortage. Hence, the economic justification of a process, without the review of relevance of its environmental impacts, it does not lead to the implementation and construction of a process plant. For this reason, it is a requirement to provide a software platform (preferably object-oriented) for quick and automatic checking of this item and the exact determining of these effects. On the other hand, due to the complexity of the... 

Advanced Persistent Threats (APTs), use hybrid, slow, and low-level patterns to leak and exfiltrate information, manipulate data, or prevent progression of a program or mission. Since current intrusion detection systems (IDSs) and alert correlation systems do not correlate low-level operating system events with network events and use alert correlation instead of event correlation, the intruders use low and hybrid events in order to make detection difficult for such detection systems. In addition, these attacks use low and slow patterns to bypass intrusion detection and alert correlation systems. Since most of the attack detection approaches use a short time-window, the slow APTs abuse this... 

Bruno Latour is one of the well-known contemporary philosophers in the field of science and technology studies. He is specially famouse for his work in laboratory studies and also for rejecting the dualities of modernity. By rejecting subject/object division, Latour opens new perpectives in Ontology. Ontology is one of the most important contributions of Latour to philosophy. He is also one of the primary developers of actor-network theory.In this research, I elaborate on ontological ideas of Latour. First, I will clarify his position in regard to modernity and show how he withdraws from dualities of modernity. Then I will explain his ontological pluralism. Based on this approach, I will... 

Today, smart devices have become an integral part of everyday life. The Android operating system is also the most popular operating system of these devices, and as a result, various malwares are produced and distributed for this operating system every day. This makes it especially important to investigate these malwares. This includes finding people involved in the development and distribution of malware, as well as discovering other malwares created by them. Discovering other involved entities, such as social media accounts, websites, Android store accounts, and taking steps to prevent malware from being distributed by them is another aspect of this story. In order to deal with organized... 

Smart devices, such as sensors, generate a wide range of data in smart homes. This collected data enables the provision of value-added services and desired features to smart home owners through IoT platforms and cloud computing systems. Numerous solutions have been proposed to protect user privacy in the IoT, including methods to counteract eavesdropping on the traffic sent from smart homes by attackers or to limit IoT platforms' access to users' sensitive information. However, particular attention has been given to solutions that focus on preserving user privacy without restricting the services users receive from cloud computing platforms. In this research, we have designed and implemented...