Sharif Digital Repository

In this thesis, the problem of secret key agreement in the channel model with side information is studiedx. In order to investigate the problem, we consider three models according to the different ways of side information availability which are the state-dependent broadcast channel; the state-dependent broadcast channel in presence of public channel and the state-dependent wiretap channel with degraded versions of the channel state information.For the problem of secret key agreement in broadcast channels, two models, the state-dependent wiretap channel and state-dependent three receivers broadcast channel, are considered. We obtain inner and outer bounds of the secret key capacity region for... 

Nowadays environment is under demolition from various aspects which the chemical pollution can be mentioned as an example. The aim of this research is to eliminate the 4nitrophenol as a pollutant through catalysis process. In the current study, to synthesis of the gold nanoparticles on the modified molybdenum de sulfide with nickel (MNi/MoS2 (M=Au, Pt)) an effective method was utilized. In the following, the structural and morphological features of the synthesized nano composites (MNi/MoS2) via different microscopic and macroscopic methods be identified. Obtained results from identification of the materials demonstrated the expected catalysts were synthesized successfully. Finally, to... 

Single-cell RNA-sequencing has opened opportunities to unlock the cell transcriptome at cellular-level resolution and investigate cell population structures and cell-type-specific gene expression patterns. Previously, we were only able to perform bulk RNA sequencing regardless of the cell type composition of cell populations. Now, with the advancements in sequencing technologies, it is possible to extract cell-level and cell-type-specific sequences, related to each type of cell separately and in a scalable and high-throughput manner. For such large studies, logistical constraints inevitably dictate that data be generated separately i.e., at different times and with different operators.... 

Plasma electrolytic oxidation (PEO) was implemented to produce a ceramic coating on AZ31 magnesium alloy, using an alternate power source (AC), in a silicate based electrolyte containing zirconia nanoparticles in different concentrations. Prior to adding nanoparticles to electrolyte, working parameters such as current density, frequency and coating duration were examined and studied concerning the equipment and coating conditions. And after reaching the optimized condition, ZrO2 nanoparticles were added to the electrolyte to create composite coatings. To examine the properties of the coatings before and after the creation of composite PEO coatings, scanning electron microscopy (SEM) was used... 

Hydrogen bond is a type of molecular bond which occurs between hydrogen and a highly electronegative atom (usually F, N and O) and results in special properties.Alkyl phosphonic acids and their derivatives have several applications as pesticides, antibiotics and anti-viruses. Furthermore, some chemicals in human nervous system hydrolyze to alkyl phosphonates and finally to methyl phosphonic acid. Linear alkyl phosphonic acids and their saults have both organic nonpolar hydrophobic groups and inorganic hydrophilic groups and used as surfactants.Different substituents can affect the acidity of alkyl phosphonic acids. Investigation have shown that hydroxyl functional group can increase the... 

Because of growing amount of data which communicated across the world, analyzing massive data set becomes more important than ever. The graph structure as an important and broadly used data structure is much more important than others. In this thesis, besides introducing the sublinear time algorithm model for massive data as a very efficient and superfast method to deal with massive data, we use them to solve problems for colored graphs. As a fundamental property, we try to compute the average of colored degree. This problem is analyzed from different aspects with various limitation. Two algorithms with multiplicative approximation factor, based on the average degree of simple graphs are... 

Drug delivery systems (DDS), which, are sensitive to tumor medium have high importance. one of the most important problem of current treatment of cancer is damage of the normal tissue, which, it is expected to solve by smart drug delivery systems. In such cases, one or more features of cancer medium cause to release of the drug. One of features of cancer medium is high concentration of reactive oxygen species and hydrogen peroxide in the most common between them. The purpose of this study is to build a drug delivery system, which it is sensitive to hydrogen peroxide. This carrier has 4 main parts. The first part is anti-cancer drug, which, it is located in the carrier. Second part is... 

With the advancement of technologies such as the Internet of Things the number of devices that are connected to the Internet are increasing rapidly and they continuously generate data that is increasing day by day. Data generation rate in these devices can be so large that practically the existing hardware has not the ability to store and process all information related to that data in appropriate way. In this situation, streaming models become more important. In the stream computing models, online processing of these data are implemented with memory complexity of O(1) . Stream algorithms refers to algorithms that input data is in the form of streams. Data appear and are removed from the... 

Recently, Polypropylene has been extensively used in a variety of applications in the polymer industry, but its quite low stiffness and toughness limit this polyolefin’s application in the engineering functions; thus, the market of polymer blend and composite manufacturing has grown noticeably in the last few years. In the current project, short Flax fibers are used in order to reinforce the PP matrix. Firstly, Flax fibers were washed with the gentle and harsh condition during the alkalization process, then the optimized alkalization condition was determined through comparison of results from X-ray Diffraction (XRD ), Attenuated Total Reflectance FTIR (ATR-FTIR) and microscopic surface... 

Polymerase chain reaction, abbreviated as PCR, is a method of amplifying the number of copies of a desired DNA sequence through special protocols. The rapid advance of microfluidic devices and the emerging concept of digital microfluidics has resulted into the development of digital droplet PCR (ddPCR) systems with their significant uses in the detection of rare mutations, cancer diagnosis, and surveillance. In this study, an integrated ddPCR microfluidic chip alongside its thermoelectric thermal cycler and optical analysis systems have been designed, fabricated and their performance has been tested and evaluated. It was shown that the effect of master mold’s surface quality, the material of... 

High-quality online services demand reliable and fast packet delivery at the network layer. However, clear evidence documents the existence of compromised routers in the ISP and enterprise networks, threatening network availability and reliability. A compromised router can stealthily drop, modify, inject, or delay packets in the forwarding path to launch Denial-of-Service, surveillance, man-in-the-middle attacks, etc. So researches tried to create intrusion detection methods to identify adversarial routers and switches. To this end, data-plane fault localization (FL) aims to identify faulty links and is an effective means of achieving high network availability. FL protocols use... 

Confining nematic liquid crystal between two curved boundary conditions while the nematic molecules have a degenerate planar anchoring leads to complex and beautiful textures of molecular disparagement(defect) in the bulk and on the surfaces. Such the liquid crystal shells are made with double-emulsion techniques in microfluidic devices have provided applications for micro-scale colloidal linkers.In this work, we have numerically minimized the elastic energy in one-constant approximation in present of Fournier’s degenerate surface potential with finite element method. The nematic shell is confined between two spherical surfaces that we have studied the final energies and their related... 

Cardiovascular signals are used to check the performance of the cardiovascular system. Researchers have always been interested in processing cardiovascular signals to achieve goals like diagnosing arrhythmias and heart diseases. The presence of causal or non-causal relationships between these signals can be used to evaluate the cardiovascular system's performance. Cardiovascular signals, such as ECG signal, RR series and systolic arterial blood pressure, chest volume or respiratory force, and blood oxygen concentration signals are used to estimate cardiovascular connectivities. There are different approaches to assessing causal relationships; among these approaches, methods based on Granger... 

A liquid crystal is a state of matter composed of highly anisotropic building blocks. When liquid crystals are exposed to surfaces with given shapes and anchoring conditions, the orientation of their molecules gets spatially disordered and topological defects may form in the system. The interplay between liquid crystals and the geometry and topology of the colloidal particles has motivated extensive recent studies.In this thesis, we present the numerical modeling results for two faceted colloidal particles in a thermotropic nematic liquid crystal. To obtain the equilibrium nematic field with a finiteelement method, we numerically minimize the free energy of the system that based on the... 

Providing high bandwidth network infrastructures for ever increasing need of data transport is of great importance. The underling infrastructure for many communication services such as GSM/3G/4G mobile networks and Internet services is Synchronous Digital Hierarchy (SDH) optical transport systems. SDH are standardized protocols that multiplex multiple lower rate digital bit streams, such as E1 and Ethernet, and transfer them synchronously over optical fiber using lasers or LEDs. In addition to high data transfer rates, flexible network management and protection mechanisms have great importance, hence are part of SDH standards. In order to obtain flexible network architecture and protected... 

Development of Smart Grid and deployment of smart meters in large scale has raised a lot of concerns regarding customers’ privacy. Consequently, several schemes have been proposed to overcome the above mentioned issue. These schemes mainly rely on data aggregation as a method of protecting users’ privacy from the grid operators. However, the main problem with most of these schemes is the fact that they require a large amount of processing power at the meter side. This, together with the fact that smart meters don’t usually have a powerful processor, can cause the unavailability of smart meter data at the required time for operators of the grid, and at the same time disables smart meters from... 

Secure routing is a major key to service maintenance in wireless ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. Wormhole attack is one of the most severe active attacks to mobile ad hoc networks. Noting the resource limitations in such networks, nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a...