Sharif Digital Repository

[No abstract available]  

Modeling languages as programming languages need precise and unambiguous semantics to be used appropriately, the formal semantics is significant for designing CASE tools and model verification. Several approaches have been used throughout these years to describe the semantics of modeling languages, but in spite of programming languages, these semantics frameworks are not used in large scale for modeling languages. This paper reviews the history of developments on semantics frameworks for modeling languages. © 2009 IEEE  

One of the services used in mobile phone is the short message service (SMS) which is widely used by the public in all parts of the world especially in Asia and Europe. This service enables people to write and exchange short messages via mobile phone. Due to the limited size of SMS, lack of a proper keyboard on the mobile phone and to improve the speed of typing, new abbreviations have been invented for different words and phrases which has lead to the invention of a new language called SMS-Textlng. One of the main issues in communication is information security and privacy. There are many methods for secret communication and many researchers are working on steganography. In steganography the... 

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... 

Much attention has been directed to different aspects of the design of pipelines. Design of the control logic of non-linear pipelines has however, been considered as a subsidiary issue in that an RTL description for such logic can easily be obtained from a behavioral description, with the use of widely available synthesis tools. But, as the complexity of a non-linear pipeline increases, so does the complexity of the control logic. The complexity may be to an extent that obtaining even a behavioral description for the control logic is rendered difficult. This paper focuses on further automating the development of systems consisting of non-linear or multi-function pipelines by proposing an... 

Arvand is the name of robots specially designed and con-structed by sharif CE team for playing soccer according to RoboCup rules and regulations for the middle size robots. Two different types of robots are made, players and the goal keeper. A player robot consists of three main parts: mechanics (motion mechanism and kicker), hard-ware (image acquisition, processing unit and control unit) and software (image processing, wireless communication, motion control and decision making). The motion mechanism is based on two drive unit, two steer units and a castor wheel. We designed a special control board which uses two microcontrollers to carry out the software system decisions and transfers them... 

Today, many students are study computer science. Although they study different courses, they rarely do homework or projects related to real world problems. In this paper, we design a project to show some of the problems which are occured during implementing a real word project to the students. In this project, the students are asked to implement the FFT (Fast Fourier Transform) algorithm on a personal computer and then port the program to a smartphone using J2ME (Java 2 Micro Edition) programming language. By doing this project, the undergraduate computer science students will become familiar with the limitations of small devices such as smartphones. They also learn the process of porting a... 

Following the expansion of Internet, many software were produced that could launch through Internet without prior installation on computers. This included game software and software that deal with financial affairs. These softwares are mainly in Java language and can be found on web pages as Java Applets. Some software owners want that their products only able to execute through their own web pages so that no one could put them on other web pages. In this paper, a new method has been presented to protect Java Applets from copying by using "Steganography in HTML web pages" method. In this method, a special 8-character string is hidden in the HTML page by a secret key. The string and the... 

This paper explores software design methodologies in the context of creating a simulator and proposes a methodology to design and implement an event-based simulator namely Sim Met. SimMet is explored in the context of the development of a complex simulator for simulating real world conditions to use in science, technology and medicine and other simulations. In this paper we interested in event-based approach to create a real world with variety range of event possibilities. The paper first discusses the role of time concept as the cornerstone of a methodical analysis and design phase. In Sim Met we use an adaptation of object-oriented methodology to meet time and event concepts in creating a... 

A comprehensive model for pervaporation in thin membrane channels was developed to study the effect of changing temperature and concentration on mass flux. This model consists of momentum, energy and species mass balances along and across the membrane in the flow channel. A computational fluid dynamics (CFD) code was written in C++ programming language to solve the coupled non-linear transport equations in the channel by finite volume method. The Semi-Implicit Pressure Link Equation (SIMPLE) CFD algorithm is used to modify the dependent variables in each of the iterations. The effect of variation of temperature and concentration on transport and thermodynamic properties were considered by... 

Establishing hidden communication is an important subject of discussion that has gained increasing importance nowadays with the development of the Internet. One of the methods introduced for establishing hidden communication is steganography. Methods of steganography have been mostly applied on images while the major characteristic of these methods is the change in the structure and features of the images so as not to be identifiable by human users. However, on the other hand, many methods have been proposed for breaking and extracting information (steganalysis) for these methods. This paper presents a method for hiding information in images by changing the appearance of the picture instead... 

Rebeca is an actor-based language for modeling concurrent and distributed systems. Its Java-like syntax makes it easy-to-use for practitioners and its formal foundation is a basis to make different formal verification approaches applicable. Compositional verification and abstraction techniques are used in formal verification of Rebeca models to overcome state explosion problems. The main contribution of this paper is to show how model checking and deduction are integrated for verifying certain properties of these models. Deduction is used to prove that abstraction techniques preserve a set of behavioral specifications in temporal logic and is also used in applying the compositional... 

In this paper, we propose extended Rebeca as a tool-supported actor-based language for modeling and verifying concurrent and distributed systems. We enrich Rebeca with a formal concept of components which integrates the message-driven computational model of actor-based languages with synchronous message passing. Components are used to encapsulate a set of internal active objects which react asynchronously to messages by means of methods and which additionally interact via a synchronous message passing mechanism. Components themselves interact only via asynchronous and anonymous messages. We present our compositional verification approach and abstraction techniques, and the theory... 

In this paper, the parallel implementations of different iterative polynomial root finding methods on a processor with SIMD processing capability are reported. These methods are based on the construction of a sequence of approximations that converge to the set of roots. We have chosen four widely used methods namely Newton's, Durand-Kerner's, Aberth-Ehrlich's, and QD and implemented them using the SIMD instruction set of the Pentium processor with C++ and assembly language. Experiments show that a speedup of 3 or higher can be achieved, depending on the order of polynomial, required accuracy, and the method employed. © 2005 IEEE  

Invention of the Internet and its spread in the world changes various aspects of human life. In addition, Internet changed human relations. Chat is one of the new aspects which invented after the Internet and is welcomed by users, especially by young people. In chat rooms, people talk with each other using text messages. Because of the need for quick typing of the word and also because of the high amount of sentences which is exchanged between users, new abbreviations are invented for various words and phrases in chat rooms. This new language is known as SMS-Texting. On the other hand, the issue of safety and security of information and especially secret relationships has led to the... 

We introduced Computed Network Process Theory to reason about protocols for mobile ad hoc networks (MANETs). Here we explore the applicability of our framework in two regards: model checking and equational reasoning. The operational semantics of our framework is based on constrained labeled transition systems (CLTSs), in which each transition label is parameterized with the set of topologies for which this transition is enabled. We illustrate how through model checking on CLTSs one can analyze mobility scenarios of MANET protocols. Furthermore, we show how by equational theory one can reason about MANETs consisting of a finite but unbounded set of nodes, in which all nodes deploy the same... 

In this study, a hydrophilic metal-organic framework (MOF) was applied to improve the performance of a cellulosic membrane for forward osmosis (FO) desalination application. The characterization results confirmed that the MOF particles existed within the matrix of the modified membrane. The MOF loading led to adjustment of the membranes in terms of overall porosity, pore inter-connectivity and hydrophilicity. These features caused an improvement in the pure water permeability (72%) and reduce the structural parameter of the modified membrane to 136 μm. The FO water flux of the modified membrane enhanced by about 180% compared to an unmodified membrane, without decreasing its selectivity. FO...