Sharif Digital Repository

SIS and SIR are common models for describing and predicting the epidemics of the contagious diseases. But these models fail to predict patterns of spreading dynamics in the case of co-infective diseases, i.e. getting infected by one disease, alters the chance of getting infected by the other one. Coinfection has been studied in the mean field approximation and on complex networks with different topologies. Another study shows temporal correlations of the underlying transmission network, play role on co-infection dynamics.In this research we investigate the effects of various temporal correlation on epidemic order parameters of independent infection and co-infection.For this purpose, we... 

Kinetics and mechanism of 4,4-dicyano-5-ethyl-1,5-heptadiene rearrangement reaction, a pericyclic type reaction, were studied with ab initio calculations in gas and solution phases. This reaction is one of the cope rearrangement in which secondary kinetic isotope effect is observed. Theoretical study on these reactions showed that probability of radicalic mechanism is inconsiderable and reaction proceeds through out a concerted mechanism with cyclic transition state. Isotope effect was studied by replacement of H1, H2 and H4,H5 with deuterium. The isotope effect data confirmed the concerted mechanism. Solvent effects on this reaction were studied by CPCM model. Solvation energies at... 

Common Object Request Broker Architecture (CORBA) is a standard for hybrid applications that is designed and supported by Object Management Group (OMG). This standard defines protocols and Relational Data Model Objects / Services which can be connected into heterogeneous software (written in different languages). So we can use CORBA to share the distributed object platform, without worrying about where they are located or who has designed them. CORBA can package the codes (in some programming languages) and add the packaging information, such as the ability to execute the codes and how to implement them. So this package or object code can execute some other programs or CORBA objects that... 

The increasing utilization of silver nanoparticles (Ag-NPs) in industrial and consumer products has raised concern to wastewater treatment utilities, due to its antimicrobial activity. In this research, recovery of silver nanoparticles from wastewater via using activated carbon and convert it into usable nanoparticles is presented. real waste of silver nanoparticles have been used and activated carbon as adsorbent has a high absorption recovery for silver. Under the optimized experimental parameters e.g. pH, temperature, time of process, and amount of activated carbon, an absorption maximum was achieved and over than 99% of silver nanoparticles can be removed from wastewater. After the... 

The purpose of this thesis is to design haptic control system for vehicle steering mechanism in a tele-driving system. Thus the subject is a developed subject in comparison with a steer by wire system. The difference is that in the steer by wire system, due to the lack of delay in sending and receiving data, possibility of instability is very low. This subject makes haptic control more difficult in vehicle tele-driving. Control of vehicle tele-driving steering system has been done by different bilateral control structures available in the literature. simulation results of the case that there is no delay in the transmission block suggest that used different control structures in order to... 

Sulfur compounds are very undesirable and result in Corrosion in metal equipment, air pollutions and poisoning of refinery Catalysts such as reforming Catalyst. Therefore, application of Hydrodesulfurization (HDS) process in order to decrease the amount of sulfur in petroleum cuts has a great importance. HDS process is the most usual and efficientmethod for sulfur removal. In this method sulfur compounds at vigorous operating conditions such as high temperature and pressure in the presence of catalyst react with hydrogen and produce hydrogen disulfide and hydrocarbon. Sulfided Co–Mo catalysts are widely used in this process.
The aim of this study is to prepare and improve CoMo/γ-Al2O3... 

An understanding of the effect of degree of cementation on static and dynamic behaviour of cemented soils is becoming increasingly important in design and analysis of geotechnical engineering problems. Naturally cemented coarse-grained soils are widely present in many parts of the world. Misunderstanding of the behaviour of such soils could lead to underestimate or overestimate of the soil parameters. Previous studies conducted by Haeri and his co-workers show that most of the alluvial deposit of Tehran, the capital city of Iran, has a soil with cemented nature. The amount and characteristics of the cementation of the deposit varies in different parts from highly cemented in the north to... 

In Hemodialysis, membrane dialyser and commonly hollow fibers are used to treat patients who suffer from end stage renal failure. When blood flows into membrane, it loses uremic toxins such as urea and creatinine. On the other hand, some of the vital proteins of blood pass through the membrane or they are adsorbed on the membrane surface. The more hydrophilicity of the membrane, the less adsorption of proteins is. In this study, to achieve high hydrophilicity and low adsorption of proteins on the polysulfone membrane surface, the presence of hydrophilic nano-particles SBA-15 in membrane composition is investigated. The nano-particles with mass percentages 0.25%, 0.5 % and 1 % to one mass 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... 

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... 

Dynamic spectrum access with the aid of cognitive radio (CR) technology is a viable solution to spectrum scarcity. There are many military and emergency applications that require the use of cognitive radio ad-hoc networks (CRAHNs). In these net- works, nodes must first find each other in a wide spectrum and then exchange their desired data. The process of finding each other in a multichannel environment is a challenging task and is usually known as rendezvous. Since rendezvous is the first step in communication, disrupting will disable the nodes from establishing proper communication sessions. That results in a drastic degrade in the performance of the network. Therefore, it is important to... 

Spray-wall impingement is one of the phenomenon that associated in different subject such as spray cooling, combustion chamber and gas turbine. With the impingement of spray to the wall, liquid film begins to form. Wall film characteristics is still an important subject to study. Due to the various stages of liquid film formation from injection of spray till spray-wall impingement, the investigation of this phenomenon is far more complicated. This paper is meant to provide detailed data on spray-wall impingement and wall film formation physics with the help of computational analysis of OpenFOAM . A Lagrangian-Eulerian method based on discrete phase model (DPM) was employed to model...