Sharif Digital Repository

Today with growth of wireless communications and progress of small and cheap sensors which have capability of communication and calculation, wireless sensor networks are important and useful topic. But due to energy restrictions, efficient use of resources and increasing network lifetime, have been considered as key factors in network design. In this regard, using efficient multicast routing in energy consumption, for an efficient data transmission to specific number of nodes instead of all nodes code updates, information requests, task assignments and etc., is necessary.On the other hand these networks use unlicensed spectrum and suffer from collision due to congestion caused by other... 

Motion simulators have been highly sought after by the growth of the aerospace industry. In the meantime, the Stewart mechanism, or the so-called Hexapads, is a robot that, in addition to being used in machining tools, is mainly used to simulate the flight. The robot is considering the project to test parts and equipment installed in marine vessels under sea movements and waves. Therefore, according to information obtained through real case studies, the purpose of this project is to design and implement a hexapad controller and user interface for samples weighing up to 2 tons which can handle linear accelerations up to 1 g, rotary accelerations up to 200 º / s2 performs at a frequency... 

Design of thick-walled spherical and cylindrical vessels as fluids containers of high gradient thermal loading is a challenging issue. Using these tanks in high pressure and temperature gradient, particularly in chemical industries, needs to use new methods in design. Elasto-Plastic solution for thick-walled hollow spherical and cylindrical tanks made of FG materials subjected to internal pressure and temperature loading is presented. The power law modeling is used for through-the-thickness variation of mechanical properties. This method is using the new advanced materials with high pressure and thermal strength in fabricating these vessels. One of these materials is functionally graded (FG)... 

This research presents scheduling of several different projects in supply chain environment which activities of these projects are performed by some contractor companies. A new practical model for solving project scheduling problem in supply chain environment is present. Multi renewable resource presents in the model of research. The research proves that the model is NP-Hard. A genetic algorithm and a simulated annealing algorithm are proposed for solving the model. The parameters of genetic algorithm such as the number of steps, the number of mutation in each step, the number of crossover in each step, the number of generation phase and also the parameters of simulated annealing algorithm... 

Circular polarization (CP) is one of the common polarization types used in wireless systems for frequency identification (RFID), global positioning (GPS) and wireless local area networks (WLAN), since it can provide greater flexibility in orientation angle between transmitter and receiver, and better mobility and weather penetration than the linearly polarized antennas. Magnetic permeability in ferrites can be tuned by external magnetic field ; So ferrites can be good candidates for new reconfigurable CP antenna technology. In this project, we will consider circularly polarized slot antenna with a wide axial ratio beamwidth that consists of a normally magnetized ferrite substrate mounted... 

In urban rail transport systems such as subway, Trains are constantly accelerate and brake, so the braking system is of great importance in energy consumption and constitute about 30 to 40 percent of total energy consumption trains, thus retrieval braking energy will lead to significant savings in urban rail transport systems. In this paper, in the beginning, different storage equipments for storage braking energy have been studied and compared and finally Supercapacitors due to technical and economic features have been selected for the storge of equipment. These systems can be implemented in both stationary and onboard. For precise evaluation and select the appropriate storage system, by... 

Now a days, the ability of measuring the mechanical properties of the living cells in in experiments has been increased. Experiments shows that the stem cells could alter their faith in different mechanical situations, but an integrated model about this phenomenon in literature has not been introduced yet. In this research thesis s minimal cell model (MMC) is developed to capture the behavior of the cells on substrates with varying mechanical properties and morphologies, MMC consists of large scale models for outer membrane of the cell and nuclear envelope, cytoplasmic area, chromatin fibers and Extra cellular matrix. Each component of the MMC will be placed in an integrated software to... 

Due to the expanding trend of using induction furnaces in Iran, the production of sponge iron at a smaller scale by Midrex method has become important. Since induction furnaces cannot benefit from the oxygen blower and foam slag like arc furnaces, the induction furnace charge should be of a higher quality. In addition, as the oxidation conditions in induction furnace are higher in comparison to arc furnaces, re-oxidation control of the induction furnace is essential. Making briquettes is one of the processes, which reduces re-oxidation during melting and since the briquette remains floated on the melt until complete melting, the lower level of briquette's contact with ambient atmosphere and... 

Due to population growth, the demand for water supply has increased. This need has drawn attention to the use of consumed and treatable water resources. Organic pollutants are a key source of water pollution. On the other hand, petrochemical oil pollution and frequent oil accidents during oil production or maritime transport have become one of the environmental problems.There are different methods for water and oil separation and water purification that in the present project, selective separation can be achieved by using hydrophobic materials and surface roughness and creating surfaces with two properties: superhydrophobic and ultra-oil friendly. This method is also very effective, cheap... 

In order to improve the efficiency of atriums, effective parameters in ventilation and acceleration of airflow are numerous. Nevertheless, parameters such as shape and height of atrium, geometry of the inlet and outlets, opening areas and the presence of heat sources in each store play a vital role. In structures higher than one floor, there is no significant airflow in the upper floors and the ventilation of atrium is unpleasant for residents. Air movement in the building is done by buoyancy-driven force and hot air upward movement due to pressure differences.This study attempts to improve the natural ventilation performance with changing mentioned parameters. So for this purpose, 3D... 

In this study, the pervaporation method was used for desulfurization of gasoline. Thiophene was used as a sulfur agent and n-heptane as a representative of hydrocarbon compounds in gasoline. The composite membranes of the active PDMS layer containing the UiO-66 metal-organic framework nanoparticles are based on porous membrane PVDF. The effect of adding PVP polymer on the porosity of the PVDF membrane has been investigated. Scanning electron microscopy (SEM), Fourier transform infrared spectrum (FTIR) and X-ray diffraction (XRD) have been used to characterize nanoparticles and synthesized membranes. The effect of adding nanoparticles on the membrane performance and its sowelling effect in... 

In its most general manner, it is possible to express equations representing the change of state variables in space and time based on three-dimensional geometry and proceed to solve this set of equations numerically. However, this approach leads to an exponential increase in computational load and a reduction in real-time performance. The use of this approach becomes necessary when access to high computational power is readily available or when a high real-time factor is not required. By employing the hybrid systems approach, which has gained popularity in the past decade, it is possible to reduce the computational load and increase the real-time factor in the simulation of the dynamic... 

This research evaluates reliability analysis on the problem of a curved beam vibration in the horizontal plane with the aim of investigating the effect of the uncertainty of the parameters of the problem on the dynamic response of the curved beam under the excitation of the moving oscillator. Curved beams are widely used in various engineering applications such as arched bridges, railway tracks and amusement park structures. However, there have been very few studies on curved beams under the stimulation caused by moving mass. Modelling the moving object as a moving oscillator, which is one of the more advanced and complete modelling of the passing vehicle, along with analyzing the... 

In this study the modeling of Bushehr power plant containment is considered. In Bushehr atomic power plant, which has a unique design, the containment is similar to PWR power plants with a metal sphere, but the installed reactor is a VVER-1000. After a full study on the containment and its systems, the required date for modeling is gathered and afterwards, the engineering handbook is prepared for MELCOR input code and then the modeling and size classification of the containment is done in 4 different ways, including the control volumes of 1, 9, 23 and 30 and then the temperature, pressure and density of hydrogen is examined. The result of studying control volume sensitivity reveals that 23... 

Learning is an essential mechanism for the survival of living things. There are different types of learning, and value learning is among the most important types. A child learns that water resolves the thirst need by repeatedly experiencing this situation. Eventually, the value of water, which has been valueless before that, increases gradually in his mind. How this concept is encoded in the brain? previous works reveal the role of different neurons and regions that are relevant to value learning. However, population analysis and dynamic modeling are less considered. Moreover, the links between different brain regions are unknown.Finding the relationship between two relevant regions of the... 

In this thesis, we studied the oscillation of neutrino flavors and the measurement of mixing parameters through the detection of cosmic neutrinos at neutrino telescopes. Most of the astrophysical explosions predict the emission of neutrino flux and kilometer-scale detectors are under construction for the observation of these neutrinos. Detection of astrophysical neutrinos opens a new window to understand the neutrino properties and also the properties of astrophysical sources.In this thesis first we review the phenomenology of neutrino flavor oscillation and characteristics of neutrino mass matrix. By introducing a new class of invariants (under general transformation of lepton fields bases)...