Sharif Digital Repository

Today, data analysis has become a valuable tool in various fields in order to discover the forms or abnormal behavior of the system. For example, detecting credit card fraud, network intrusion, or detecting defects in sensors. In this thesis, a method for fault analysis is presented, which can be used as a monitoring tool to monitor the data that is received in a time series from an Internet of Things system and understand the behavior of the system. This method is designed in such a way that by matching the components with the input data, in general, it is applicable for our desired time series. The presented algorithm is implemented in an unsupervised environment using a statistical... 

Statistical mechanics offers an important outlook for studying rough surfaces. Loop model is one of the effective statistical methods for study of surfaces. We present and analyze this method for characterization of the morphology of rough surfaces. By statistics of contour loops which could be obtained from an ensemble of a surface such as the SOS model, one can calculate fractal dimension, loops’ length and the probability of connection of two points by a certain loop, etc. Armed with these results, critical exponents in two dimensions are exactly obtainable. In this thesis, after reviewing the properties of different rough surfaces, we shall pursue some results on statistical analysis of... 

Three dimensional or vertical integration is a new way of increasing the performance and expanding the capacities of modern integrated circuits. Using this technology, 3D Networks on Chip has been proposed as one of the novel research fields and has been receiving a lot of attention. 3D Networks on chip have a lot of benefits such as capability of large scale integration, increasing the density of elements on chip and expanding the dimensions of chips. Large scale integration and increasing density of elements will cause more consumption of energy. This more energy consumption will cause high temperature in chips. Although high temperature has been managed in 2D networks, but necessity of... 

Classical quench is the act of sudden change in the temperature of a system. This process is not new and has been used in some branches of science, like the smithing industry to produce a hard and stiff metal objects. Quantum Quench is the deformation of system's Hamiltonian in short time interval. This quantum version of quench is around for a few years and has attracted a lot of attention after its experimental realization in Ultracold Atoms setup. Suppose we have hamiltonian which depends on the constant g_0 which is the dynamical parameter of the system. It could be interaction strength between elements in the system or the external electric field amplitude on the system. At an arbitrary... 

The dimer model studies random dimer covers of a graph. A dimer cover is a subset of the edges of the graph such that each vertex is the endpoint of exactly one edge.The double-dimer model is a natural generalization of the dimer model, whose configuration is a union of two dimer covers, which ends up a set of even-length simple loops and doubled edges.The goal of this thesis is the study of statistical properties of very long doubledimer loops in very large lattices. To this end, we use the Grassmannian representation of the dimer model to compute some loop-related observables in rectangular domains of the square lattice, i.e. 1) the probability distribution of the number of nontrivial... 

Non-deterministic finite automata (NFA) are an elementary type of Turing machines with very high processing power. NFA processors provide parallelism at the data and task level because they can be in several different output states in one clock cycle. Implementing such machines with memory is a good strategy because if we consider each of the memory columns as a state, by selecting a row of the memory, we can activate several states at the same time, which is an implementation of NFA. NFA-based automata processors were first introduced by Micron and were very powerful for issues such as pattern matching, DNA sequencing, or regular expressions and, in general, for machine learning topics.... 

With increasing number of processors on a chip, the role of interconnections becomes more important in both power consumption and bandwidth. As a result, in MultiProcessor System-on-Chip architectures, the design constraints will shift from "Computational Constraints" to "Communicational Constraints". Nowadays, optical information transfer is introduced as a suitable substitution for electrical interconnections in chips, which can eliminate their problems. Many different optical networks have been presented so far. These networks can be divided into two subcategories. Networks of the first category use an electrical infrastructure as well as optical one. Hence, the scalability of scheme is... 

We study different aspects of non-relativistic conformal symmetries. Schrodinger and Galilean Conformal Algebra (GCA) are reviewed extensively. We as well study possible extensions of non-relativistic conformal symmetries. We find a new class of infinite dimensional non-relativistic conformal symmetries in 2+1. We study logarithmic representation of Schrodinger symmetry. As well we utilize contraction approach and obtain both ordinary and logarithmic representations of GCA. Finally we investigate some aspects of logarithmic GCA in the context of holography principle  

Discretely holomorphic observables have recently been proposed for two dimensional lattice models at criticality, whose correlation functions satisfy a discrete version of Cauchy-Riemann relations. Existence of these observables appears to have a deep relation with integrability of the model. On the other hand at critical points of these models, there exist entities known as discrete parafermions whose Boltzmann weights satisfy the Yang-Baxter Equations. For this reason, finding parafermionic observables in any lattice model is equivalent to proof of solvability. This thesis is a step towards understanding the relation between Parafermions and Solvability. For instance, the Boltzmann weights... 

Power law behavior of earthquakes has been a matter of interest for many scientists. One on these power laws known as Gutenberg-Richter law describes the magnitude distribution of earthquakes. The Burridge-Knopoff model of faults, produces the same power law distribution of events as the Gutenberg-Richter law for earthquakes. Olami, Feder and Christensen in 1992, introduced a 2-D, continues sand pile model Known as OFC that displays self-organized-criticality. They claimed that this model is equivalent to Burridge-Knopoff model. It means that criticality is the origin of power law behavior of the Burridge-Knopoff model. Nevertheless, there are some evidence against criticality in the... 

The increasing complexity of embedded systems has led to the integration of tasks with various degrees of criticality on a common hardware platform called a mixed-criticality system. These systems typically exploit the inherent redundancy of multicore systems to employ the fault-tolerant techniques to satisfy the required target reliability. On the other hand, the use of fault-tolerant techniques increases the time that cores are simultaneously active with maximum power, which can violate the thermal design power (TDP) and exceed the safe temperature of the chip. This activates the dynamic thermal manage- ment (DTM) technique. Some of the most well-known methods to reduce the chip surface... 

Phenomena such as will and volition, the emergence of qualities, internal and external feelings are the main problems related to consciousness. Consciousness is one of the oldest and, of course, most complex problems in science, and scientists are striving to provide a suitable explanation for this problem, but a complete answer has not yet been presented. Quantum consciousness is also an attempt to provide a suitable answer using the theory of quantum mechanics as the most fundamental scientific theory regarding the behavior of matter. In this area, the Orch OR theory by Penrose-Hameroff, the Henry P. Stap’s theory of quantum consciousness, and the Eccles-Beck’s theory of quantum... 

Combination of 3D IC technology and network on chip (NoC) is an effective solution to increase system scalability, and also alleviate the interconnect problem in large scale integrated circuits. However, due to the increased power density in 3D NoC systems and the destructive impact of high temperatures on chip reliability, applying thermal management solutions becomes crucial in such circuits. Since hardware thermal control techniques, such as DVFS, can cause significant degradation on chip performance, in this thesis we propose a runtime distributed migration algorithm based on game theory to balance the heat dissipation among processing elements (PEs) in 3D NoCs. The objective of this... 

In the Pay-TV industry, it is necessary to limit access of unauthorized users. Conditional Access System (CAS) is the solution. In the Pay-TV, the ability of instant join and leave operation is desirable for users. On the other hand, this characteristic is in contradiction with growth of user number.
Previous proposed conditional access systems address the requirement of pay-TV from several aspects. Key distribution management is on of them which plays a key role in the security and efficiency of a conditional access system. Re-examining the process of key distribution management make it possible to find a way to provide a greater flexibility for the users.
The purpose of this... 

When a submarine pipeline is laid, pipeline spans may exist due to the unevenness of the seabed. Such pipeline spans when exposed to currents, may undergo vortex-induced vibration (VIV). As the flow velocity increases, the cross-flow oscillation begins to occur and vortex shedding frequency may approach the natural frequency of the pipe span. Amplified response due to resonance between the vortex shedding frequency of the free span may cause fatigue damage. Thus, the determination of the critical allowable span length under the various environments becomes the most challenging areas in the offshore industry. A substantial research effort related to various aspects of VIV and free span...