Sharif Digital Repository

Today, the internal connections of the CPUs with a few billion wired transistors in 14 copper layers on the silicon wafer are possible. Recently, power dissipation has slowed the growth rate of clock growth in CPUs, and nowadays sometimes more than 60% power is lost in connections. In this situation, the increase in efficiency has been achieved in accordance with Moore's law with multi-core chips. This theme has made the connections between the cores much more important than before. Usually the information in the network structure on chip (NOC) is transmitted on these connections. Therefore, all three aspects of delay, power dissipation and bit rate are important for communication channels.... 

Developing and progressing excavation technology, and distillation and petroleum technology as fuel cause chemical and hydrocarbonic materials have been given an important role in human life. Having petroleum expanded, its effect in countries’ economics has been highlighted and found a substantial role in countries’ development. Iran, considering 11% extractable petroleum reserves which is equivalent to 138 billion barrel, is known as an oil rich country. The petroleum has an eminent role in country’s economics and is the main country’s income source and the most important exports. With regard to the high technology needed for petroleum exploration and purification, Iran requires foreign... 

In recent years, there has been an increasing interest in posturography methods as an objective quantitative tool for assessing balance and indicating patient with high risk of fall. Although many posturographic studies tried to describe balance deficiencies in PD, little success has been achieved in utilizing static posturography as a tool for discriminating faller and non-faller PD patients. Furthermore, Dynamic posturography studies have delivered valuable insight into the potentiality of these methods for assessing balance, but these devices are very high in price and cumbersome to move that can limit the feasibility of their use in the clinical settings. The aims of this study were: 1)... 

Self-organized critical phenomena are interesting phenomena which are ubiquitous in nature. Examples include mountain ranges , coastlines and also activities in the hu-man's brain. In these processes, without fine-tuning of any external parameter such as the temperature, the system exhibits critical behavior. In other words, the dynamics of the system, drives it towards an state in which long range correlations in space and scaling behaviors can be seen.The first successful model which could characterize such systems was BTW model, introduced by Bak , Tang and Wiesenfeld in 1987. This model, later named Abelian sandpile model, was very simple and because of this simplicity, a large amount of... 

Bonding gravity with Quantum mechanics has always been a challenging issue. So that, accomplishing a theory of quantum gravity is one of the most important research topics in High-Energy Physics.Information paradox in black holes is among such issues which connect quantum mechanics with gravity. Black holes as a natural solution of Einstein equations have a distinction, with other solutions, since there exists an event horizon that imparts space-time into two causally disconnected regions.According to Hawking’s calculations, black holes would evaporate over time by the thermal radiation. This resulting thermal radiation has less information than the initial collapsed matter in a pure state.... 

Aspect-Oriented Programming is a software engineering paradigm that offers new constructs, such as join points, pointcuts, advices and aspects in order to improve separation of crosscutting concerns. The new constructs bring new type of programming faults with respect to crosscutting concerns, such as incorrect pointcuts, advice or aspect precedence. In fact, existing object-oriented testing techniques are not adequate for testing aspect-oriented programs. As a result, new testing techniques must be developed. In this paper, an approach based upon UML sequence diagrams for testing aspect- oriented program is presented. The proposed approach focuses on integration of one or several... 

Using revenue management in any industry can increase the profit. In aviation industries, due to the huge number of requests and travels for each airline, a revenue management system can lead to a good profit for the airlines. The first step in revenue management system is predicting the demand.In this article two models are developed using time series techniques, based on the information taken from one of the Iranian airlines in Tehran-Mashhad fly route.The first model is developed using ARIMA and seasonal-ARIMA models and the second one is based on the demand and price history, price in the day of prediction and the ARIMA model. The second model which is a combination of price, prior price... 

This thesis proposes a dynamic model for studding influences of suspension components behavior on rail vehicle dynamics. As the air springs are very important isolating component in rail vehicles, a new complete nonlinear air spring model, with taking into consideration of thermo–dynamical effects, is developed. The model coefficients are tuned based on the real test data and it can be easily used in dynamic modeling of air springs. The new proposed vehicle model is a complete track–vehicle model with 70 degree of freedoms which is addressed as a modular type. Experimental results from complete rail–vehicle field test, showed remarkable agreement between proposed model and test results.... 

Advances in IC fabrication makes possible have systems on chips. In this thesis we have designed and fabricated a digitally controlled bias chip for a transceiver which can be programmed by its digital interface. In this thesis, briefly we review basics of voltage regulators and methods for controlling them. Then we introduce high voltage 0.18um CMOS technology. In this thesis, we describe the requirements of a specific transceiver and present a system to overcome these requirements. This system has positive, negative and internal regulators, a five-bit analog to digital converter, temperature sensors, power amplifier controller and digital serial interface. In this thesis, we present a... 

Mobile edge computing (MEC) is a promising technology that aims to resolve cloud computing’s issues by deploying computation resources at the edge of mobile network and in the proximity of users. The advantages of MEC include reduced latency, energy consumption, and load on access and mobile core networks, to name but a few. Despite all the aforementioned advantages, the mobility of mobile network users causes the traditional MEC architecture to suffer from several issues, such as decreased efficiency and frequent service interruption. One of the methods to manage users’ mobility is virtual machine (VM) migration, where the VM containing the user’s task is migrated to somewhere closer to... 

In the presented dissertation an analytical model is developed for the air gap flux density and the cogging torque in the axial flux surface-mounted PM machines. The slotting effect is taken into account in the magnetic flux distribution.The model is derived from solving the 2D Poisson' equation in the slotted air gap. To simplify the solution process, the concept of the uniqueness theorem is used to replace the slotted air gap by a slotless one and some surface current distribution. In addition, the separation of variables method is applied to the analytical solution of the Poisson equation. However, the proposed 2D analytical model is developed for the quasi 3D model by the well-known... 

Isfahan Zirconium Production Plant (ZPP) is one of the most important plants in the nuclear industry of Islamic Republic of Iran. The wastewater of this plant contains high values of Sodium, Chloride, Nitrate and low values of Calcium, Magnesium, Zinc and Zirconium ions. Its release has been banned by international and national law because of the dangers and toxicity of its ions for the environment and living organisms. Therefore, its refinement as a compensation of Iran’s water resources in agriculture and drinking water has received a major consideration. Among the common methods to removal of these ions, membrane process method is selected due to it's major benefits such as not producing...