Sharif Digital Repository

By the immense growth of the Web-Based Social Networks (WBSNs), the role of trust in connecting people together through WBSNs is getting more important than ever. In other words, since the probability of malicious behavior in WBSNs is increasing, it is necessary to evaluate the reliability of a person before trying to communicate with. Hence, it is desirable to find out how much a person should trust another one in a network. The approach to answer this question is usually called trust inference. In this paper, we propose a new trust inference algorithm (Called RN-Trust) based on the resistive networks concept. The algorithm, in addition to being simple, resolves some problems of previously... 

Recommendation plays an increasingly important role in our daily lives. Recommender systems automatically suggest items to users that might be interesting for them. Recent studies illustrate that incorporating social trust in Matrix Factorization methods demonstrably improves accuracy of rating prediction. Such approaches mainly use the trust scores explicitly expressed by users. However, it is often challenging to have users provide explicit trust scores of each other. There exist quite a few works, which propose Trust Metrics to compute and predict trust scores between users based on their interactions. In this paper, first we present how social relation can be extracted from users'... 

Recommendation plays an increasingly important role in our daily lives. Recommender systems automatically suggest items to users that might be interesting for them. Recent studies illustrate that incorporating social trust in Matrix Factorization methods demonstrably improves accuracy of rating prediction. Such approaches mainly use the trust scores explicitly expressed by users. However, it is often challenging to have users provide explicit trust scores of each other. There exist quite a few works, which propose Trust Metrics to compute and predict trust scores between users based on their interactions. In this paper, first we present how social relation can be extracted from users'... 

Many real-world systems and applications such as World Wide Web, and social interactions can be modeled as networks of interacting nodes. However, in many cases, one encounters the situation where the pattern of the node-to-node interactions (i.e., edges) or the structure of a network is unknown. We address this issue by studying the Network Reconstruction Problem: Given a network with missing edges, how is it possible to uncover the network structure based on certain observable quantities extracted from partial measurements? We propose a novel framework called CS-NetRec based on a newly emerged paradigm in sparse signal recovery called Compressive Sensing (CS). The results demonstrate that... 

Nowadays, a great amount of information is circulated through the Internet. Some of them exclusively belong to a special group of users and require protection and safeguarding against unauthorized access. To this end, a category of systems called HIP (Human Interactive Proof) are designed to distinguish between various groups of users. An important task on the Internet websites is registration. Some hackers write programs to make fake registration that waste the resources of the web sites or even stop them from providing services. Therefore, human users should be distinguished from computer programs. CAPTCHA (Completely Automatic Public Turing Test to Tell Computer and Human Apart) methods... 

There are many websites on the Internet which are for adult users and we want to restrict access to them for adults only. Adult content filtering programs on client computers are the current available solutions. But if we can identify the child users at server side, we can protect the children more. In this paper, we try to answer the question that whether it is possible to identify child users or not? © 2008 SICE  

In some websites it is necessary to distinguishing between human users and computer programs which is known as CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart). CAPTCHA methods are mainly based on the weak points of OCR systems and using them are undesirable to human users. In this paper a method has been presented for distinguishing between human users and computer programs on the basis of choice of an object shown on the screen. In this method some objects are chosen randomly and the pictures of these topics are downloaded from the Internet. Then after applying some effects such as rotation, all of the pictures are shown on the screen. Then we ask the... 

Nowadays, many daily human activities such as education, commerce, talks, etc. are carried out through the Internet. In cases such as the registering in websites, some hackers write programs to make automatic false enrolments which waste the resources of the website while this may even stop the entire website from working. Therefore, it is necessary to tell apart human users from computer programs which is known as CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart). CAPTCHA methods are mainly based on the weak points of OCR (Optical Character Recognition) systems while using them are undesirable to human users. So the Non-OCR-Based CAPTCHA methods are... 

Currently, many daily human activities such as education, commerce and talks are carried out through the Internet. In cases such as the registering in websites, some hackers write programs to make automatic false enrolments which waste the resources of the website while this may even stop the entire website from working. Therefore, it is necessary to tell apart human users from computer programs which is known as CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart). CAPTCHA methods are mainly based on the weak points of OCR (Optical Character Recognition) systems while using them are undesirable to human users. In this paper a method has been presented for... 

There are many sites specially designed for mobile phones. In cases such as the registering in websites, some hackers write programs to make automatic false enrolments which waste the resources of the website. Therefore, it is necessary to distinguish between human users and computer programs. These systems are known as CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart). CAPTCHA methods are mainly based on the weak points of OCR (Optical Character Recognition) systems while using them difficult in tools such as PDAs (Personal Digital Assistant) or mobile phones that lack a big keyboard. So the Non-OCR-Based CAPTCHA methods are proposed which are do not need... 

Nowadays the Internet users are from different ages and groups. The disabled people also use the Internet. Some websites are especially created for disabled people. Many Internet sites offers services for human users, but unfortunately some computer programs are designed to abuse these services. To solve this problem, some systems named CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart) have been introduced to distinguish between human users and computer programs. CAPTCHA methods are mainly based on the weaknesses of OCR systems while using them is undesirable for human users, especially for disabled people. Therefore some CAPTCHA methods are designed... 

Nowadays the Internet users are from different ages and groups. Disabled people are a group of the Internet users. Some websites are especially created for these people. One group of the disabled people are deaf persons. They have a special talking language which is named sign language. Here we present a method to encourage them, esp. children, to learn the sign language. In this method, when a deaf person wants to enter a website which is created for deaf persons, a word is shown as a movie using a sign language. The user should recognize the word and select it from a list. If the user understands the sign language and recognizes the word, he/she can enter the website. This project has been... 

Nowadays, many daily human activities such as education, commerce, talks, etc. are carried out through the Internet. In cases such as the registering in websites, some hackers write programs to make automatic false enrolments which waste the resources of the website while this may even stop the entire website from working. Therefore, it is necessary to tell apart human users from computer programs which is known as CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart). CAPTCHA methods are mainly based on the weak points of OCR (Optical Character Recognition) systems while using them are undesirable to human users. In this paper a method has been presented for... 

Nowadays the Internet users are from different ages and groups. The disabled people also use the Internet. Some websites are especially created for disabled people. Many Internet sites offers services for human users, but unfortunately some computer programs are designed which abuse these services. As a result some systems named CAPTCHA (Completely Automated Public Turing test to tell Computers and Human Apart) have been introduced to tell apart human users and computer software. In this paper, a new CAPTCHA method is introduced which can be used by blindpeople. In this method a simple mathematicalproblem is created according to predefined patterns and converted to speech using a... 

One of the important yet insufficiently studied subjects in fair allocation is the externality effect among agents. For a resource allocation problem, externalities imply that the share allocated to an agent may affect the utilities of other agents. In this paper, we conduct a study of fair allocation of indivisible goods when the externalities are not negligible. Inspired by the models in the context of network diffusion, we present a simple and natural model, namely network externalities, to capture the externalities. To evaluate fairness in the network externalities model, we generalize the idea behind the notion of maximin-share (MMS) to achieve a new criterion, namely,... 

Recent years have witnessed an explosion in the availability of news articles on the World Wide Web. In addition, organizing the results of a news search facilitates the user(s) in overviewing the returned news. In this work, we have focused on the label-based clustering approaches for news meta-search engines, and which clusters news articles based on their topics. Furthermore, our engine for NEws meta-Search REsult Clustering (NeSReC) is implemented along. NeSReC takes queries from the users and collect the snippets of news which are retrieved by The Altavista News Search Engine for the queries. Afterwards, it performs the hierarchical clustering and labeling based on news snippets in a... 

Web services foster functionality of current web to service oriented architecture. Nascent semantic web is capable of automating activities by annotating shared ontological semantics to documents and services. Although, a zillion web services with diversity have been made since the inception of its diffusion, it is not a panacea for software development and it is still in its infancy. A middle agent (broker) simplifies the interaction of service providers and service requester, especially in the case that an atomic web service cannot fulfill user's need. The broker composes a desired value-added service and orchestrates the execution of bundled sub-processes. It is inevitable that several... 

XML has emerged as a common standard for data exchange over the World Wide Web. One way to manage XML data is to use the power of relational databases for storing and querying them. So the hierarchical XML data should be mapped into flat relational structure. In this paper we propose an algorithm which maps DTD to relational schema and as well as content and structure it preserves the functional dependencies during the mapping process in order to produce relations with less redundancy. This is done by categorizing functional dependencies and introducing four rules to be applied to the relations created by the hybrid inlining algorithm according to each category. These rules will reduce... 

Ontology Aligning is an answer to the problem of handling heterogenous information on different domains. After application of some measures, one reaches a set of similarity values. The final goal is to extract mappings. Our contribution is to introduce a new genetic algorithm (GA) based extraction method. The GA, employs a structured based weighting model, named "coincidence based model", as its fitness function. In the first part of the paper, some preliminaries and notations are given and then we introduce the coincidence based weighting. In the second part the paper discusses the details of the devised GA with the evaluation results for a sample dataset  

Nowadays web services composition that presents capabilities in response to customers' complex requirements has a special importance in real businesses. However, service choreography as a form of service composition, still faces many challenges. One of the most important challenges of the choreography domain is how to validate the model based on the corresponding requirements. To this end, in this paper processes choreographies are modeled using the interaction view of BPMN 2.0 standard. Then, goal modeling is suggested to extract the requirements. For each requirement all possible valid scenarios are considered and finally using Savara tool, the requirements' scenarios are modeled and the...