Sharif Digital Repository

Knowledge graphs are structured data sources which are widely used in the information process techniques. There are general and specialized knowledge graphs out there. These graphs will be used as the kernel of future search engines. Due to the lack of proper and tested Persian knowledge graphs, a method for knowledge graph extraction from news sources of the web has been introduced in this research.A knowledge graph extraction system from the unstructured web sources has been implemented in this research. In order to achieve this, a training dataset for the classifier was first extracted from semi-structured data of Wikipedia pages. At that time sentences were extracted from the... 

In recent years, cloud computing has provided a well-known platform to provide on-the-fly and cost-efficient services on local and world area networks. As a result, the number of cloud data centers is increasing due to the increasing number of customers. For this reason, the energy consumption of numerous cloud data centers is one of the biggest bottlenecks for cloud providers. In general, various hardware and software-based solutions can be used to optimize power consumption at the same time of guaranty service level agreements. One of the most popular of these software-based solutions is dynamic allocation of resources to virtual machines (VM), i.e. a sandboxing technique responsible for... 

The progress and development in the field of Natural Language Processing (NLP) have led to the emergence of Natural Language Understanding (NLU). One of the main objectives in this field is inference, deduction, or entailment from the phrases (sentences) of a natural language. The crucial question here is whether it is possible to semantically infer a natural language hypothesis from a set of natural language premises. Since in many applications of Natural Language Inference (NLI) in the real world, it has a decisive role, this problem is of the utmost importance. Furthermore, the previously proposed approaches to tackle this problem incorporate a wide range of classic logic-based and new... 

In order to use the high performance capabilities of a computing system, first it is required to provide a proper modelling for the job and the system's environment. Second, it is required to design scheduling and offloading algorithms based on the job and the system modeling and third for evaluating the performance of these algorithms. It is needed to either simulate them or prove their approximation factors. This project aims to carry out these three parts for the Edge Computing environment. The laid out model of the system in this thesis consists of many devices that are distributed around the network, which they can execute tasks parallel to each other, and between each two devices there... 

As one of the most important software artifacts, release reports include most essential changes of software systems in each release. These reports are useful for documenting team activities, improving communication between team members and facilitating decision makings. They are often generated manually by a team member, which can be a tedious and time-consuming task. For each release, one should go through hundreds of issue reports, changed files, source code, and other related documents to determine what has changed and why. Then they need to identify the most important and relevant changes. Therefore, automated generation of release reports can be highly desirable. Despite the... 

The main spectrum of a location search engine is retrieving the locations that are most relevant to the user query. Geographic and spatial queries usually consist of a series of keywords that express the user's needs. The geographic search engine should retrieve the locations associated with the user request and then rank the retrieved results according to their relevance to the user request. In some cases, user requests may contain spelling errors that can greatly affect the results retrieved. Spell correction is automatic in the back spectrum recovery system. Spelling correction is the task of automatically recovering the intended text from a misspelled text. Therefore, spelling correction... 

Common Object Request Broker Architecture (CORBA) is a standard for hybrid applications that is designed and supported by Object Management Group (OMG). This standard defines protocols and Relational Data Model Objects / Services which can be connected into heterogeneous software (written in different languages). So we can use CORBA to share the distributed object platform, without worrying about where they are located or who has designed them. CORBA can package the codes (in some programming languages) and add the packaging information, such as the ability to execute the codes and how to implement them. So this package or object code can execute some other programs or CORBA objects that... 

In this study the concept of the origin of life, as an important question, is investigated and reviewed.Then the possibility of the beginning of life from an extraterrestrial origin is studied via spectroscopy methods to analyze the role of the cosmic waves.Moreover, by considering the similarity between the chirality of the essential amino acids and extraterrestrial amino acids, found in meteors the various methods for studying the structure of molecules, as well as the possibility of the transfer of the central elements of life from space to the earth are reviewed in details.Finally, we suggest how chirality might be emerged due to the interaction of the molecule with the environment,... 

The purpose of this dissertation is proposing a probabilistic model in transition systems of records. In these systems, two acceptance state of finite and infinite string have proposed which acceptance state of finite string is called probabilistic finite automata of records and acceptance state of infinite string is called probabilistic buchi automata of records. The buchi automata of records is an operational semantic for Reo coordination language. Reo is a coordination language to coordinate existing component of a component based system. Reo circuits with non-deterministic and probabilistic channel can be modeled by proposing probabilistic buchi automata of records. In this dissertation... 

The main goal of this thesis is to verify real-time properties of timed coordinated systems specified by timed-Reo circuits using the model checking techniqe. We use Timed Buchi Automata of Records (TBAR) as the semantics of timed-Reo. The model checking is done by converting Timed Buchi Automata of Records to an extension of Timed Automata that are usingas input of UPPAAL tool. We introduce a writer-automaton, which is synchronous with the desired Timed Automata, for initializing input ports. A tool that transforms Timed Buchi Automata of Records to UPPAAL Timed Automata has been implemented. Finally, two model checking case studies are examined by usingof our implemented tool over UPPAAL  

In a distributed system, each solution for the problem of Byzantine Agreement requires that some of correct processes reach a common decision value from a set of proposed values while Byzantine processes may behave arbitrary. This problem is one of the most fundamental problems in the theory of distributed systems. While the problem has been widely studied in fully-connected fixed networks, few studies have been carried out in the context of self-organizing mobile networks such as Mobile Ad-Hoc Networks.
This research presents a randomized consensus protocol with three additional modules for the case of dynamic networks: Participant Detectors, Failure Detectors and Maintainer. We assume... 

Approximate Agreement (AA) is one of the most important issues in distributed networks in which non-faulty processes execute a voting algorithm to reach the values that are very close to each other. AA for Partially Connected Networks (PCNs) is very limited because a node may not have a complete view of the whole network which makes it difficult to reach the convergence. This research proposes a convergent Fuzzy algorithm for synchronous distributed networks in the presence of faulty or Byzantine processes. When each node receives a new value from its neighbors,it runs the convergent Fuzzy algorithm. If the received value is not in the expected range of values, the processor can discard the... 

In this thesis the usage of probabilistic reasoning in collaborative filtering is investigated. The problem of predicting users' rating is formulated as a Bayesian decision problem and a generative probabilistic model is used in order to find the optimal decision. Two different probabilistic models are considered: user based model and rating based model. In user based model prediction of ratings is based on structural learning of Bayesian networks. In rating based model, we assume a predefined Bayesian network represents the joint distribution over model variables and rating prediction is carried out using McMc inference method. MovieLens dataset is chosen to evaluate and compare the results... 

The World Wide Web has been experiencing a massive growth regarding its content and users in recent years; therefore the need for effective means of accessing and processing available items has attracted a wide range of researchers and industries. Recommender systems has emerged to help both users to find what they may be interested in and the producers to sell their products more efficiently. As the number of these techniques grow, the need to evaluate them properly increases as well. However the proposed evaluation metrics are very diverse and often inconsistent with each other. Although there had been immense research in this field, there is no united and proper approach for evaluation of...