Sharif Digital Repository

One of the main challenges in characterization and simulation of larg scale porous media is spatial heterogeneity and variability of porous media properties such as porosity, density, and lithology at different scales. These information can be achieved at different scale from coring, well logging or seismic data. Well logs are an efficient way to obtain rock and fluid properties of geological patterns specially water resources and hydrocarbon reservoirs. One of the characteristics of geophysical well logs is their complex behavior which seems to imply a multifractal nature.In this study we investigate multifractality and presence of long range correlations in petrophysical well log data such... 

In this thesis we consider transmitting an analog Gaussian source over an AWGN channel in the presence of an interference completely known at the transmitter intwo cases: 1) Compression bandwidth with interference uncorrelated with the sourceand 2) Matched bandwidth channel in the presence of interference correlated withthe source to be transmitted. We study joint source-channel coding schemes basedon hybrid digital-analog (HDA) codes. After providng a brief review, we will proposetwo new schemes for the ?rst case and one novel scheme for the second case. Aswe will see both schemes for the ?rst case achieve the optimal mean-squared error(MSE) distortion. The proposed HDA schemes can... 

As mobile networks have been expanded, the importance of subscribers' information security has become more and more evident. Despite mitigating known vulnerabilities of older mobile networks in newer generations, there are still some security flaws that can be exploited. In particular, as a common scenario, attackers can exploit "Use 2G mobile network if 3G/4G is unavailable" setting in order to force a subscriber to downgrade his/her mobile network to 2G; hence becoming vulnerable to known 2G attacks. Mobile networks have a heterogeneous and distributed architecture which make intrusion detection systems incapable of covering the entire network. In this dissertation, alongside with the... 

Quantitative motion quality evaluation has been always of much significance for CVA patients, especially the HCP ones. The purpose of the present study is to introduce and analyze the efficiency of a novel index, namely “Consumed Energy Index”, for evaluating the quality of the motions performed by HCP patients. For this purpose, Firstly, a Musculo-Skeletal model of the human arm was provided on Matlab and OpenSim softwares, with four DoFs: three DoFs at shoulder and one DoF at elbow joint as well as eight muscles. The muscles are in pairs of flexor-extensor at each DoF. The model is capable of receiving Cartesian trajectories for joints and solving inverse kinematics and dynamics to obtain... 

Advanced Persistent Threats (APTs) by multi step , low-level and sometimes slowmoving behaviors try to hiding malicious behaviors. These attacks are complex, costly and the attacker violates the security policy explicitly or implicitly by distributing his or her behavior to multi agents and infiltrate trusted subjects. One of the challenges is the discovery of these attacks in the early stages of the attack and before the complete violation of confidentiality. the lack of deep intercepting of events, content with intrusion detection systems warnings, the lack of simultaneous tracking of host and network-level events and the lack of real-time processing is limitations of existing detection... 

The study of thermodynamics of small-scale systems or quantum thermodynamics has been recently receiving a lot of attention from quantum scientists in the field of quantum information. The main purpose of this thesis is to review the effects of quantum phenomena such as correlations, on the laws of thermodynamics and specifically on the efficiency of quantum heat engines. We first review some of the most important topics of classical thermodynamics such as the laws of thermodynamics, thermodynamic potentials and heat engines. The trade-off between power and efficiency for classical heat engines is investigated. It is shown that, this is impossible to have a heat engine performing with the... 

Examining composite quantum systems through quantum thermodynamics, we face the new concept of binding energy. In this thesis, we are going to present a general definition for binding energy in quantum systems which covers any kind of interactions. First of all, we examine the possibility of energy exchange in a quantum system using quantum thermodynamics. In this theory, energy exchanges of an open quantum system may be divided in to two portions: heat and work; due to an accepted definition, heat is the portion of energy that is supposed to change entropy, while work has no influence on that. In this research, we restrict our calculations to the systems which are thermally closed and... 

Precise leak detection by acoustic signal analysis calls for robust similarity measures to estimate the time delay between recorded leakage signals and minimize the probability of false alarms, in the face of dispersive propagation, multiple reflections, and unknown correlated, uncorrelated and impulsive background noise. Providing evidence that higher order modes and multi-reflected signals behave like sets of correlated noise, this thesis uses a regression model to optimize residual complexity in the presence of both correlated and uncorrelated noise. This optimized residual complexity (ORC) is highly robust since it takes into account both the level and complexity of noise and signal,... 

In the extensive horizon of artificial intelligence technology, one of the grand challenges in computer vision has been semantic segmentation. This task which aimed to predict label for each pixel of image, describes the scene, due to the need of low level information, is more complicated in comparison with other computer vision tasks. However, as part of concept of scene understanding and a crucial step in many real world applications such as autonomous driving, human-computer interaction and robot navigation, many researchers have been sought to resolve it. What makes this task more challenging rather than other computer vision tasks is that information beyond a pixel, its neighbors and... 

In recent decades, the trend towards renewable energy sources has increased dramatically. Rising fossil fuel prices and concerns about the effects of greenhouse gases and carbon dioxide emissions have drawn the attention of many energy experts to the use of renewable energy sources such as wind farms as an alternative to fossil fuel energy sources. Therefore, the issue of reliability related to these sources and whether such units can be considered as a source of generation has gained more importance. Due to the random nature of wind power, the share of these power plants in providing system adequacy is less than their nominal value. Therefore, determining the capacity value of wind power... 

Electrical systems are prone to voltage or current unbalance due to unbalance loads or asymmetries in network elements such as untransposed lines. Voltage and current unbalance can cause malfunction or reduction in lifetime of different elements. Voltage unbalance has been studied in a variety of publications, due to its high importance and significant effects. However, current unbalance has not gained much attention despite its undeniable influence on transformers’ and line’s lifetime. Observing high values of current unbalance in LV systems is predictable and inevitable. On the other hand, HV systems must be much more balance due to their different structure and absence of large unbalance...