Sharif Digital Repository

Rough surfaces and growth process are the important and significant problems of theoretical and condensed matter physics to model phenomena ranging from the extremely small (biological phenomena) to largest one (Earth’s relief). Although the equations that describe these processes are well defined, but the question of how to characterize these surfaces which display large fluctuations, is open. The existence of (often) scale invariant clusters and very large fluctuations in surface growth process are reminiscent of critical fluctuations in equilibrium systems. Therefore, it is natural to try characterizing the surface by means of critical exponents, i.e., by the scaling dimensions of various... 

One of the most famous attacks through the internet is the phishing attack. There have been several tools which have been applied in order to discover and confront against this type of attack. Since attackers can change their approaches by spending little cost, they apply methods in order to elude these tools. One of the tricks which has been popular between attackers recently is utilization of Fast-Flux Service Networks. By using these destructive networks, recognition of the main server becomes more complicated. Therefore, the server obtains more accessibility in comparison to the past situation and the life time becomes longer.In this thesis, by collecting data of Sharif server and... 

Diagnostic and prognostic of spall defect in the rolling element bearings is investigated in this thesis. A new numerical model is proposed which considers defect size, defect clearance and defect roughness. The results of this model based on surface roughness show superior similarity to experimental data than classic model. To improve diagnostic ability in the rolling element bearings, four new methods are proposed in this thesis. These methods are short-time statistical features, local curve roughness, level crossing and wavelet packet decomposition. These methods are applied in outer ring, inner ring and ball defects and it is showed that these methods have better detection ability... 

Kardar-Parisi-Zhang (KPZ) equation was first proposed as a model to explain surface growth. This equation is very similar to Edwards-Wilkinson (EW) equation that is used to study scaling phenomena in non-equilibrium systems and phase transition. Although EW’s universality classes have been known well, it still remains a problem for KPZ. In the present thesis, in addition to a general review on surface growth models and a study on properties of rough surfaces, we study the physics of the KPZ model and the other related physical models. Also, using numerical results (like SLE method), renormalization group results and simulation, we study the dynamic and roughness exponents (α, z), and the... 

With progress in integrated circuits technology, on chip systems have become operational, and after that, onchip network are as solutions to improve onchip connections and also its scalability. With improving technology, the number of cores on chips can be more, that it causes increasing importance of produced problems by parallel links. Serial links are one of the methods to decrease these problems. Serial links have some advantages in compare with parallel links in some aspects like: clock pulse skew, cross talk, area cost, difficulties in wiring and synchronizing clock pulse signals. But any way, problems such as high operational frequency and complicated serializer and deserializer... 

Recent advances in VLSI technology have led to integrate a few billion transistors on a chip. Systems on Chip provide solutions to the design problems of these systems. As technology scales down to deep sub-micron dimensions, the delay and power consumption of global interconnects become the major bottleneck in SoC design. Networks on Chip (NoCs) have been proposed as an efficient, scalable, modular and reliable solution to provide on chip communication in large VLSI design. The market trend to mobile digital systems and battery-powered devices add power as a new dimension to VLSI design space in addition to speed and area. Interconnect wires dissipate a significant fraction of power... 

According to prediction of ITRS, power consumption and bandwidth of processors' interconnection, will be the most major bottleneck of the System-on- Chips (SoCs) in the future. Therefore, in MultiProcessor System-on-Chip (MPSoC) architectures, the design constraints will be altered from "Computational Constraints" to "Communicational Constraints". There are three kinds of communications in the surface of the chip: Global, median and local. The main difference between global and local connections is that the length of latter one will be changed with technology. In other words, it is scalable like processor's elements while the length of global connections is practically constant. Even though... 

Nowadays, a large proportion of the power consumption in high-performance multi-processor architectures on chip belongs to connections. Reducing power consumption while maintaining high efficiency in these architectures is one of the main concerns. Networks on Chip (NoC) originally were introduced to improve efficiency, but now, given the importance of power, we must provide some solutions to reduce power consumption, and delay in NOCs. Connections in chip can be divided into three categories: global, intermediate and local, while the length of global connections is almost constant in different scales, local connections are scalable. As a result improving efficiency of a small number of... 

Brown and Henneaux showed that asymptotic symmetries of asymptotically form a conformal group in two dimensions [1]. Also they could derive classical central charge of theory. Fourteen years later, Maldacena, conjectured that this Holographic correspondence could be true for a specific theory a simplified chromodynamics in the boundary of ), this holographic theory attracted physicist communitee's attention. Many physicists tried to make this conjecture more precise. It is worth to say that, no example of holographic correspondence has been completely proven, till now, Because of the difficulty of the calculation. However these days we consider Madacena conjectrure in any arbitrary... 

Recently, a new tool in the study of two-dimensional continuous phase transition was provided by Schramm-Loewner evolution. The main part of SLE is a conformal map which relates growth process of a two-dimensional simple curve to one-dimensional motion on the real axis (so-called Loewner driving function). Time evolution of this map and Loewner driving function is connected via the Loewner differential equation. It turns out that for a certain class of stochastic and conformally invariant curves in two dimensions, the driving function shows Brownian motion in one dimension. Strength point of SLE comes from this fact that all the geometrical properties of such curves is described through a... 

According to power limitation on a chip and the need to simultaneously access high utilization and low power consumption, Multi-Processor System-on-Chip (MPSoC) architectures have been introduced. The major part of power consumption in a network on chip belongs to interconnects. One of the most important issues is to decrease power consumption while maintaining high utilization. The ability of optical interconnects in decreasing power consumption and increasing utilization has introduced a new architecture called optical network on chip. This architecture uses the benefits of optical signals and elements in order to transfer data. In this thesis, we introduce a new architecture with... 

Nowadays by increasing the number of processing cores in system-on-chip, using networks-on-chip, as an optimized interconnection foundation for transferring data between processing cores is inevitable .Based on this, the necessity of designing and implementing an optimized structure for testing network-on-chip, considering various overheads such as power consumption, latency, bandwidth and area, becomes an important issue in designing network-on-chip. The purpose of this project is to design an optimized structure for testing routers and connecting links in network, which considers power consumption overhead, latency and area overhead on one hand, and fault coverage on the other hand.... 

Schramm Loewner evolution (SLE) is a one-parameter family of random simple curves in the complex plane introduced by Schramm in 1999 which is believed to describe the scaling limit of a variety of domain interfaces at criticality. This thesis is concerned with statistical properties of watersheds dividing drainage basins. The fractal dimension of this model is 1.22 which is consistent with the known fractal dimension for several important models such as Invasion percolation and minimum spanning trees (MST). We present numerical evidences that in the scaling limit this model are SLE curves with =1.73, being the only known physical example of an
SLE with <2. This lies outside the... 

As the number of processing cores on a single chip continues to grow, the need for a high band width, low power communication structure, will be the most important requirements of next generation chip multiprocessors. Today, a major part of power consumption in multi core architectures belongs to interconnects. Due to these facts, reducing consuming power, as well as supporting high performance, is concerned in these architectures. The concept of “network-on-chip” emerged to improve the performance of CMPs. But now a day, considering the circumstances of power budges, it’s incapable of presenting new strategies to decrease consuming power and delay. However, optical interconnects have the... 

In this thesis, a hardware is designed and implemented for testing the perfoemance of MIMO communication systems in LTE standard using SCM channel model. This hardware can be used for measuring the BER of 2x2 wireless systems. This hardware is the first channel emulator, with hardware implementation which is using SCM channel model and implementation of a similar one has not been reported.In addition to the implementation of the mentioned channel emulator, a new approach is used for implementing a Gaussian variate generator (GVG) which is implemented on both FPGA and ASIC and shows better characteristics in comparison with the works done in the past. ASIC implementation of this part is done... 

With constant increase in the rate of VLSI circuits manufactured in sites separate from the designers and computer architects, global concern regarding the possibility of integration of malware by the manufacturing foundries has arisen. Particularly, one main issue that affects reliability of the chips is modifications or additions with malicious intention,known as Hardware Trojans, which are easily applicable during design and manufacturing phase of chips. There has been an increasing fraud in chip-set manufacturing. Hardware Trojans may leak confidential information outside the chip, to the attacker, may alter the function of circuit, or completely fail a system. Hence search for new... 

Today's latest technology integrated circuits are manufactured for a wide range of applications. With the constant increase in the usage rate of integrated circuits, designing a high reliable system is of utmost importance. The avoidance of counterfeit components is a major challenge of hardware security and trust. Counterfeit components cause lower performance and reduced life span. They are of great concern to the manufacturers and consumers of electronic systems, impacting the security and reliability of these systems. If these parts end up in critical applications like medical systems, satellites, aerospace, or power plants, the results could be catastrophic. So far, there are different... 

With constant increase in the rate of VLSI circuits manufactured in sites separate from the designers and computer architects, global concern regarding the possibility of integration of malware by the manufacturing foundries has arisen. Particularly, one main issue that affects relability of the chips is modifications or additions with malicious intension, known as Harware Trojans, which are easily applicable during design and manufacturing phase of chip. This study intends to introduce a model based on the scan chain, a method is provided for intellectual property protection. Currently available IP protection solutions are usually limited to protect single FPGA configurations and require... 

Nowadays integrated circuits are extremely vulnerable to hardware trojans (HT). Hardware trojans can be injected into the ICs in design or fabricate phase, and damage system’s functionality or security. In this thesis, we first describe hardware trojan definition, classification and types of HTs, negative effects, detection ways and analysis of them. Then we propose a new solution in order to solve the negative points of previous methods