Sharif Digital Repository

In this paper1 we consider higher isoperimetric numbers of a (finite directed) graph. In this regard we focus on the nth mean isoperimetric constant of a directed graph as the minimum of the mean outgoing normalized flows from a given set of n disjoint subsets of the vertex set of the graph. We show that the second mean isoperimetric constant in this general setting, coincides with (the mean version of) the classical Cheeger constant of the graph, while for the rest of the spectrum we show that there is a fundamental difference between the nth isoperimetric constant and the number obtained by taking the minimum over all n-partitions. In this direction, we show that our definition is the... 

Integrating high spatial resolution of functional magnetic resonance imaging (fMRI) and high temporal resolution of electroencephalogram (EEG) is promising in simultaneous EEG and fMRI analysis, especially for epileptic patients. The EEG recorded inside an MR scanner is interfered with MR artifacts. In this article, we propose new artifact reduction approaches and compare them with the conventional artifact reduction methods. Our proposed approaches are based on generalized eigenvalue decomposition (GEVD) and median filtering. The proposed methods are applied on experimental simultaneous EEG and fMRI recordings of an epileptic patient. The results show significant improvement over... 

Network traffic classification has become more important with the rapid growth of Internet and online applications. Numerous studies have been done on this topic which have led to many different approaches. Most of these approaches use predefined features extracted by an expert in order to classify network traffic. In contrast, in this study, we propose a deep learning-based approach which integrates both feature extraction and classification phases into one system. Our proposed scheme, called “Deep Packet,” can handle both traffic characterization in which the network traffic is categorized into major classes (e.g., FTP and P2P) and application identification in which identifying end-user... 

In many fast MR imaging techniques, K-space is sampled sparsely in order to gain a fast traverse of K-space. These techniques use non-Cartesian sampling trajectories like radial, zigzag, and spiral. In the reconstruction procedure, usually interpolation methods are used to obtain missing samples on a regular grid. In this paper, we propose an iterative method for image reconstruction which uses the black marginal area of the image. The proposed iterative solution offers a great enhancement in the quality of the reconstructed image in comparison with conventional algorithms like zero filling and neural network. This method is applied on MRI data and its improved performance over other methods... 

Utilizing the Finite Element Method (FEM), the strain field in the radial forging process of tube is calculated at different process conditions and compared with the experimental results achieved using the microhardness test. The effect of various process parameters such as friction, axial feed, back push and front pull forces and die angles on the strain field are investigated. Using the results of the analysis, it is shown that the deformation inhomogeneity, introduced by an Inhomogeneity Factor (IF), is maximum in the inner zone of tube, while the minimum and the maximum effective strains are appeared at the inner zone of tube and about the core of the tube thickness, respectively. Also,... 

Restricting children access to materials unsuitable for them such as violence scenes is very important for parents. So there is a feature named Parental Control in devices such as televisions and computers to define the contents children can access. The parental control setting must be protected from children and is usually done by a password. In this paper, we propose a new method for distinguishing between adult users and child users based on human speech. In our proposed method, the user must say a word and the adult users are identified by processing the speech. Our current implementation has 92.5% accuracy for distinguishing adult users from children. © 2008 IEEE  

Digital music technologies enable users to create and use large collections of music. One of the desirable features for users is the ability to automatically organize the collection and search in it. One of the operations that they need is automatic identification of tracks' artists. This operation can be used to automatically classify new added tracks to a collection. Additionally, the user can use this operation to identify the artist of an unknown track. The artist name of a track can help the user find similar music. In this paper, we introduce a fast and scalable system that can automatically identify the artist of music tracks. This system is creating a signature for each track that is... 

Background: Angiogenesis inhibition research is a cutting edge area in angiogenesis-dependent disease therapy, especially in cancer therapy. Recently, studies on anti-angiogenic peptides have provided promising results in the field of cancer treatment. Methods: A non-redundant dataset of 135 anti-angiogenic peptides (positive instances) and 135 non anti-angiogenic peptides (negative instances) was used in this study. Also, 20% of each class were selected to construct an independent test dataset (see Additional files 1, 2). We proposed an effective machine learning based R package (AntAngioCOOL) to predict anti-angiogenic peptides. We have examined more than 200 different classifiers to build... 

Multimedia files including audio, music and movies are important part of resources available on the Internet. With the expansion of personal computers and other digital devices such as digital cameras, ordinary people are also creating different multimedia files. Hence, there are huge amount of multimedia files in the Internet. Considering the volume of files available, we need automatic methods for indexing, classification and retrieval of multimedia files. But, there are a number of problems in processing multimedia files. Two important issues are the large size of multimedia files and different lengths of different files. In this PhD project, we want to develop a solution for these two... 

Speech is one of the main communication methods used by humans. So designing speech based interfaces for computer applications can ease the use of them for different users, especially disabled and elderly people. In this project, we want to design and implement a system that can identify user's group from his/her speech. We are working on two main applications: Parental Control and Completely Automated Public Turing test to tell Computers and Human Apart (CAPTCHA). In the Parental Control application, we want to distinguish between child users and adults based on human speech. This can be used to restrict child user access to adult materials such as adult websites. In the CAPTCHA... 

Upon development of m-commerce as one of the new branches of e-commerce, m-banking has emerged as one of the main divisions of m-commerce. As the m-banking was received very well, it has embarked upon supply of various services based on different systems and with the aid of various services such as the Short Messaging Service (SMS). However, in spite of its advantages, m-banking is facing some challenges as well. One of these challenges is the issue of security of this system. This paper presents a method for increasing security of the information requested by users with the use of steganography method. In this method, instead of direct sending of the information, it is hidden in a picture... 

The hidden, real-time sending and display of information, esp. in public places, has since long received attention and faced many challenges. Therefore, different methods have been proposed so far for hiding information in different cover media. In this paper I propose a new method for the real-time hiding of information without need to any storage cover media. This method is based on the real-time hiding of information in output screens of the instrument (such as screens shown by the monitor). This method of steganography is very similar to the two discussions of image steganography and video steganography. The idea suggested in this paper was simulated on a PC computer by using the Pascal... 

One of the important issues in security fields is hidden exchange of information. There are different methods for this purpose such as cryptography and steganography. Steganography is a method of hiding data within a cover media so that other individuals fail to realize their existence. In this paper a new method for steganography in English texts is proposed. In this method the US and UK spellings of words substituted in order to hide data in an English text. For example "color" has different spelling in UK (colour) and US (color). Therefore the data can be hidden in the text by substituting these words  

After rapid growth of the Internet, establishing hidden communication is an important subject of security that has gained increasing importance. One of the methods for establishing hidden communication is steganography. On the other hand with the expanding the use of mobile phones mobile telecommunication companies starting to add additional features to their mobile phones such as MMS (Multimedia Messaging Service) in order to attract more customers. Considering above statements, steganography in MMS messages is a good solution for establishing hidden communication. In this paper a new method for steganography in MMS messages using both text and image steganography methods is presented. This... 

In recent years by growing computer applications, new technologies are also invented. Meanwhile new issues are faced such as security. One of the security areas is hidden exchange of information which contains methods such as cryptography and steganography. Steganography is the art of hiding data in a cover media such as image or sound. In this paper a new method for Steganography in Persian and Arabic texts is presented. In this method pseudo-space character is used for hiding the data. This character prevents the Persian and Arabic letters from joining but without adding a space between the two and keeps the words closer together. Its code is 200C in Unicode hex notation. This character... 

After the emergence of modern technologies in the field of information technologies (IT), virtual learning has attained a new form. The way of announcing exams' grades is an important topic in e-learning. For announcing exams' grades on the web, various methods have been proposed. In this paper, first some common methods for announcing students' grades are reviewed, then three new methods which are named "Virtual Grade", "Steganography Grades", and "Grade HIP" are introduced and the result of implementing these methods for announcing the grades of some courses at the some Iranian universities are provided. Also these methods and their results are analyzed. Finally these three new methods are...