Sharif Digital Repository

Compressed sensing theory with the goal of sparse recovery using as few measurements as possible, has found much attention in the past decade. A fundamental assumption in compresses sensing is the linear nature of the measurements, that establishes a matrix equation between the unknowns and unknowns. However, in some applications, the physics of the problem may impose some type of nonlinear relationship between the unknowns and the measurements. Some solutions concerned with this type of problems,approximate the nonlinear relationship using a second order Taylor expansion. Using this approximation besides some modifications in the way the second order relationship is presented, a more simple... 

Trasmission system is one of the most important parts of the power system which not only creates an interface between generation and distribution section, but also provides a reliable and non-descriminated environment between them. In recent years, restructuring is introduced in many countries of the world. The competition is begun in generation section while, the transmission section was remained monopoly. Private investors don't have enough incentive to invest in this section, because, the presence of uncertainties have made decision making hard for them and increased the investment risk. On the other hand, with increase in consumption and generation, need to invest in this section seems... 

A fully coupled numerical model is developed for the modeling of the cracks in porous media with flow of two fluids using the extended finite element method.The governing equations of two-phase fluid flow in deformable porous media, which account for the coupling between various physical phenomena, are derived within the framework of the generalized Biot theory. The solid phase displacement, the wetting phase pressure and the capillary pressure are taken as the primary variables of the formulation. The other variables are incorporated into the model via the experimentally determined functions that specify the relationship between the hydraulic properties of the porous medium, i.e.... 

The visible growth in usage of computer networks in daily human life has significantly increased the importance of their correct and flawless operation. Various solutions have been offered to evaluate the operation correctness of network equipment. One of the most important issues in this context is evaluating the performance of such equipment. Due to the increase in speed of network ports, design and implementation of performance evaluation tools have become a challenging issue in terms of parameters such as speed, time accuracy, power consumption and cost. In this thesis, a hardware-based system for testing network equipment with 10 Gbps ports has been designed and implemented. This system... 

Payload Attribution Systems (PAS) are one of the most important tools of network forensics for detecting offenders and victims after the occurrence of a cybercrime. A PAS stores the network traffic history in order to detect the source and destination pair of a certain data stream in case a malicious activity occurs on the network. The huge volume of information that is daily transferred in the network means that the data stored by a PAS must be as compact and concise as possible. Moreover, the investigation of this large volume of data for a malicious data stream must be handled within a reasonable time. For this purpose, several techniques based on storing a digest of traffic using Bloom... 

Daily improvements in technology and exchanging important information via internet and connection networks make data and connection security a significant problem. Cryptology is the branch of knowledge which concerns secret communications in all of its aspects. Two major areas of cryptology are cryptography and cryptanalysis. Cryptography is a branch of cryptology concerned with protecting communications from being read by unauthorized people.
Cryptologists design and create algorithms to improve cryptography along with finding methods to crack those algorithms. Cryptanalysis is a branch of cryptology concerned with cracking the cryptographic systems used by others.
Cryptographic... 

Deterministic and Predictable behaviors are two important constraints in real-time embedded systems. Using cache memories alongside of CPUs may lead to nondeterministic and unpredictable behaviors in embedded systems. To avoid these behaviors, embedded system designers use Scratchpad Memories (SPMs). In addition, using embedded systems in safty-critical applications need to include reliability and fault tolerance. The first challenge to using SPM is the management of its contents,called SPM Mapping. SPM Mappingconsists of three important parts:1) Determining the most frequent parts of programs, 2) Efficient assignment of SPM area to those parts, and 3) Controlling the transitions of those... 

In machine learning, classification is of great importance. Unlike the traditional single-label classification in which one instance can have only one label, in multi-label classification tasks, an instance can be associated with a set of labels. Multi-label classifiers have to address many problems including: considering correlations between labels, handling large-scale datasets with many instances and a large set of labels, and having only a fraction of valid label assignments in the training set. To tackle datasets with a large set of labels, recently embedding-based methods have been proposed which seek to represent the label assignments in an intermediate space. Subsequently, given the... 

In this study, in the base case using a modeling system WRF=CAMx Distribution concentration of all pollutants from mobile sources in an episode of 60 days (November and December 2015) is calculated in Tehran. In this context, the emissions inventory related to mobile sources outputs the code in Fortran and WRF meteorological model to model air quality prepared and then using the CAMx, Tehran’s air quality is simulated. In order to verification in this case, the results of pollutant concentration NO2, CO, PM2٫5, with concentrations of air pollution monitoring stations compared. Given that in this study the concentration of pollutants from mobile sources is modeled, predicted by the model,... 

With the technology scaling trend in recent years, leakage power has become a major challenge for SRAM-based on-chip memories. According to the recent reports, SRAM-based on-chip memories contribute to more than half of the processors’ power consumption. Accordingly, in recent years, researchers have tried to find an alternative technology for SRAMs in on-chip memories. The International Technology Roadmap for Semiconductors (ITRS) recently announced that STT-MRAMs are the most promising technology to replace SRAMs. While STT-MRAMs benefit from low energy consumption, high endurance, and high density compared to other non-volatile memory technologies, comparing with SRAMs, STT-MRAMs have... 

Nowadays, intracellular studies have been widely developed in biological applications. Intracellular analysis requires direct experiments on cells such as cell separation, purification, lysis and DNA extraction. The process of cell lysis and the resulting DNA purification is a crucial step in diagnostic processes. Since, the basis of many genetic studies is the information existed in double-stranded DNA structures.In this project, a microfluidic system is presented which performs integrated chemical cell lysis and DNA extraction. The cell used in this study is L-929. In order to increase cell lysis, the serpentine micromixer in combination with internal and external barriers at the beginning... 

Due to the urgent need for early diagnosis of many blood and gastrointestinal diseases, the development and optimization of rapid diagnosis kits is considered important. One of the best ways to make these kits is to use paper microfluidics. The paper platform is inexpensive and compatible with diagnostic processes and can enable rapid and high-sensitivity detection. In the present study, filter paper has been used as the main platform and hydrophobic channels have been created with the help of a hydrophobic marker to guide the fluid on the paper substrate. To perform the detection process, color changes resulting from the aggregation of nanoparticles on the paper are used. In this case, in... 

Skin, as the largest organ of the body and the first protector against external injuries, plays an important role in maintaining human health. Therefore, providing a method for complete treatment of skin lesions is very important. In the last century, tissue engineering approaches, with the introduction of skin scaffolds, have been instrumental in the process of skin tissue regeneration and treatment. The aim of the present study is to construct an optimal bilayer scaffold to mimic the two outer layer of the skin (epidermis and dermis). Besides, the effects of placenta extract on acceleration of wound healing was investigated by an in-vivo test. both layer of scaffold are porous hydrogels,... 

Research in the field of financial market prediction has always been an intriguing subject for academic researchers and stock traders, despite its associated complexities and challenges. Accurately forecasting stock prices and market indices is considered a complex task due to their nonlinear and dynamic nature, requiring analysis of intricate time series data. Over time, various models such as regression models, classification methods, statistical techniques, and artificial intelligence algorithms have been used to predict these variables. With the advancement of technology and the development of AI-based models, particularly machine learning models, along with the availability of vast... 

Routers play a key role in transferring information between various Networks. It is very important to make sure about the compatibility of OSPF in a router with its standard description. In this regard, before presenting or applying a router and also evaluating its performance, it is necessary to carry out conformance test with the help of network equipment testers Tester designers extract test cases from protocol standard description through non-formal ways and exam them on network equipment.
In this thesis, a part of OSFP protocol has been modeled through colored Petri nets. In this regard, two sections of OSPF RFC have been model checked: neighbor state machine and data base... 

Focus of the present research is on the study and cognition of sources of carbonaceous compounds present in PM2.5, particularly secondary organic carbon. For this purpose, two different approaches were used. The first approach investigates the SOA formation from internal combustion engines exhaust and unburned fuel (bottom-up approach). The second approach studies the contribution of each of the primary and secondary sources to PM2.5 mass, whereby secondary organic carbon share is obtained (top-down approach). Modeling SOA formation from vehicles exhaust showed that diesel vehicles have greater SOA formation potential than gasoline vehicles, due to large amount of S/IVOCs present in their... 

Electrospray is a process in which the charged liquid is subjected to the effect of an electric field and after passing through an emitter, it will propagate in the form of jets or small droplets. This process is used in applications such as electric thrusters, cooling or mass spectrometry. In the electronics industry, cooling high-temperature microprocessors is a challenge. In this regard, air-based cooling systems are not well able to discharge heat from electrical and electronic components. Electrospray cooling technology is one of the new and promising methods. In this research, the two-dimensional simulation of electrospray cooling is performed by using COMSOL commercial software as a... 

Wireless sensor networks (WSNs) are composed of many independent spatially-distributed sensor nodes where communicate their information acquired from environment to shape a uniform view of their managed scope. Using WSNs in places which human can hardly attend uninterruptedly, as well as constraints such as low power consumption, low price, small size, and limited radio range, are the biggest challenges for researchers and WSN designers. Supplying security is yet another common challenge of using these networks. The beginning chapters of this dissertation introduce the most important security mechanisms in WSNs, that is, key management and cryptography. Since each application has its own... 

Transport phenomena in porous media play important role in many areas of subsurface hydrology, geo-physics, environment, energy and petroleum. The work in the field of numerical modeling of fractured porous media is yet an open area of research. The classic finite element method (FEM) has some limitations in modeling of discontinuities like fracture. FEM mesh should conform with the geometry of the fracture. Presence of fracture imposes discontinuity in pressure field of fluid phases and displacement field of solid phase (rock). To represent the fractures, the extended finite element method (X-FEM) can be used in which the standard finite element approximation of the field variables is...