Sharif Digital Repository

Benzene is one of the most famous aromatic compounds characterized by ringing and stability, which is formed by both natural processes and human activities. Benzene is also a substance found in hydrocarbons such as gasoline and hexane. International organizations for cancer research and global health have identified benzene as a carcinogen. Also, polymer grade hexane and in fact the same benzene-free hexane is widely used in the petrochemical and lubrication industries (food industry) of the country, which also requires reducing benzene from 6 to 2% to less than 50% ppm. Since partial and selective hydrogenation of benzene is performed because it is a heterogeneous process, ie at the surface... 

Nowadays network marketing has promoted marketing, sale and customer relationship altogether. On the other hand, due to the growth of internet, network marketing has become a powerful and attractive channel that can be utilized alongside the other traditional channel. Pricing and network marketing structure influences on distribution system coordination and networker motivation in network marketing. This thesis provides a framework to study the integration of network marketing with retailers in a dual channel distribution system and provide the pattern for determining the different variables of distribution systems, including of product price in diverse channels, commission payment to... 

Gas injection as an enhanced oil recovery (EOR) method usually suffers from low recovery efficiency. The low viscosity and density of gas as well as reservoir heterogeneity are the main reasons of early breakthrough and override of gas in oil reservoirs. To mitigate the poor sweep efficiency of gas injection, surfactants can be co-injected or injected in an alternating manner with gas to form foam within the reservoir rock. The foam formation can reduce the mobility of the injection fluids in porous media. A significant challenge of foam injection is the stability of the foam in formations and the foam liquid drainage rate is one of the key factors which characterize or show the efficiency... 

technologies for cooling of electronic devices, have high efficiency due to the heat transfer in two-phase state. In this project, experimental effects of asymmetric triangle groove has been studied on the boiling fluid and effect of the motion on the boiling and heat pipe. Therefore, the experiment has been done by 3 heat pipes and each with 3 plates. The plates consist of a smooth plate, a plate with triangle groove and a plate with rectangle groove. Each heat pipe was filled by methanol in volumetric percentage from 10 to 60. The results show that 20 percent methanol is the optimum for all kind of heat pipe, which has been used. In addition, it is shown that heat pipe with triangle groove... 

Time-dependent origin-destination demand is a key input in dynamic traffic assignment in advanced traffic management systems, and the result of dynamic traffic assignment is dependent on the accuracy of this information. One method to achieve time dependent demand matrices is using a primary demand matrix and volume traffic counts in some links of network. In this thesis a bi-level model is used to correct the demand matrix and the extended gradient method is suggested to solve the problem. The extended gradient is an iterative method that in each iteration, corrects the demand matrix in a way that the estimated traffic flow be close to the observed traffic flow. Execution of this method in... 

Anti-lock brakes car as one of the most fundamental and vehicle stability control system is considered. Solenoid valves, one-way valves, Accumulator, damper orifices and other components is a crucial role in the anti-lock system performance, so that the performance of the system and thus affect the dynamic performance of the vehicle. This is the most important part of the anti-lock brake System and These components are all new brake system.In this study a complete modeling of hydraulic control unit and obtain sufficient data to model the dynamic behavior of the hydraulic control unit to be seen. operators working in higher frequencies are weak and virtually reached saturation and efficient... 

The discovery of the iron-based superconductors attracted much experimental and theoretical attention in the recent years. BaFe2As2 is one of the highlighted materials which is the antiferromagnetic metal (below Neel temperature) and undergoes to superconducting and non-magnetic state by variety of doping, usually accompanied by a structural phase transition. Superconductivity is appeared in this system by doping Co and Ni at the Fe sites which is one of the excited situations in the physics of superconductors, where the magnetic doping suppresses the superconducting state. So, the study of Co doping of the electronic structure of this system, might lead us to better understanding of the... 

Nowadays, image registration is considered as one of usual issues in medical researches whose new findings are expanding outstandingly and it has reached a high level of maturity. Generally speaking, image registration is a task to reliably estimate the geometric transformation such that two images can be precisely aligned. With respect to different uses of image registration in medical applications, it has attracted the attention of many scholars and there has been made significant improvement in this realm. Image registration is still one of the active branches in medical image processing due to its wide applications and problems. Graphs, thanks to their geometric structures and intuitive... 

Energy efficiency in desalination systems is primarily hindered by high-energy-consuming equipment, such as compressors. This study explores a novel cycle of combined ejector desalination involving a two-phase state and a solar vacuum tube collector designed to generate saturated steam at a lower temperature. The mechanism involves water entering the ejector's primary nozzle in the liquid phase, pulling steam generated by the collector at a reduced pressure and temperature. This process facilitates the separation of desalinated water from saltwater, resulting in purified water in a variable phase. The performance of the ejector was thoroughly evaluated, including how primary and secondary... 

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... 

In this research work an analytical instrument has been developed for assessment of energy technologies, R&D resource allocation and technology development. Development of new technologies has been considered according to the specific conditions of developing countries. The analytical instrument includes two models interlinked with each other: energy technology assessment and optimal control of innovation activities. Energy technology assessment and prioritization of new energy technologies are provided by the model of the energy supply system that contains a detailed representation of current and emerging technologies characterized in terms of their technical indices. The results of this... 

In the last three decades, the world has experienced enormous increases in energy consumption as a consequence of the economic and population growth. This causes renewable energy and energy recovery to become a requirement in building designs rather than option. A direct expansion (DX) air conditioning system is an efficient way to supply fresh and dehumidified air to a built environment a long side it plays a key role in preventing the spread of respiratory diseases. To improve the efficiency of a conventional DX system in hot and humid regions, fresh air dehumidification and conditioning systems with energy recovery measures are the key equipment to reach such a goal. To achieve this goal... 

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...