Sharif Digital Repository

The main object of this thesis is synthesizing poly(vinyl acetate)/ colloidal silica nanocomposites via emulsion and in-situ polymerization methods. At the first, nanocomposites were produced in the presence of poly(vinyl alcohol) as the protective colloid, ammonium persulphate as the initiator and sodium bicarbonate as the buffer in an aqueous solution. Then, structural, thermal, rheological, mechanical and surface properties of produced nanocomposites with various colloidal silica content (0.5 %, 1 %, 1.5 %) were evaluated by DLS, FTIR, SEM-EDS, DSC, TGA, dynamic and steady rheological tests, tensile and shear mechanical tests, AFM and static water contact angle. The particle size of... 

In this thesis, zero-divisor ideal graphs and geometric zero-divisor graphs are introduced and are partially studied. We begin by studying the relation between the zero-divisor graph and zero-divisor ideal graph associated to principal ideal rings. We also investigate some of the basic properties of the zero-divisor ideal graphs, including their girth and diameter. Then, we introduce the geometric zero-divisor graphs associated to reduced schemes and study their basic properties to some extent. Finally, we conclude by characterizing all reduced schemes whose associated geometric zero-divisor graph contains a vertex which is... 

Industrial parks represent integrated industrial systems where it helps implementing efficient measures for managing natural and fossil fuel resources and their impact on environment quality. In Iran, the most industrial parks have faced serious problems due to the irreversible effects on ecosystems. mass/energy flows management and optimization based on industrial ecology, can lead to minimizing the environmental impacts and to maximizing the value added of industrial parks simultaneously. In the present research, sustainable development in Siri island as Eco-industrial park in Iran has been investigated. The island includes: extraction, separation, operation and transportation of crude oil... 

Magnetic levitation is an appropriate solution for noncontact 3D manipulation. Workspace of the previously proposed maglev systems is confined to a relatively small cube, which severely limits the application of this technology. In addition, most of the previously given mechanisms require the design and application of a subsystem in order to unify their magnetic field. In this paper, a moving magnet is proposed which results in a horizontally extendable workspace; moreover, the field unifying section is not needed since one electromagnet only is used. Further, details of the mechanism and finite element based design procedure of the magnet are presented. Dynamic equations of the system... 

One of the frequent aspects of lawlessness at signalized intersections, is red-light violation (RLV). In addition to its adverse effect on intersection safety, RLV can cause delay in the startup of the vehicles in the next phase defined as “green flow”. In this research, in order to investigate the adverse effect of RLV, the required data were collected from two signalized intersections in the City of Esfahan, Iran using recording cameras. Then, using a cellular network in the intersections and the Aimsun traffic simulation software, the effects of RLV on the delay, capacity, and level of service of the intersections were evaluated. The results show that the behavior of the drivers in the... 

During the recent years, the emerging technology of photonic, on-chip communication has been widely explored to resolve the problems of traditional electrical communication in terms of performance and power consumption. Micro-Resonator (MR) as the photonic building block for optical comunication is very sensitive to temperature and process variation. Variation of resonance wavelength of a micro-resonator as a result of temperature fluctuations causes tremendous error for optical data routing through the waveguides, and reduce the reliability of network. A temperature-aware routing algorithm enables the network to tolerate fault and continue working properly. Temperature variation of MRs is a... 

In this thesis, we address the problem of joint Range, Angle and Doppler frequency estimation in FDA-MIMO radars. Target parameter estimation is among the most important areas of research in radar signal processing. In this field of research, there are numerous challenges to overcome, including low estimation accuracy, a scarcity of snapshots, and the high computational complexity of algorithms. For this reason, diverse methods have been developed to solve this problem. Each of these methods has its own features and capabilities, focusing on one or more of the existing challenges. The application of these methods also depends on various factors, including the signal structure, which is... 

The present study is work on fabrication and characterization of a chitosan/ gelatin/ Mg substituted hydroxyapatite nano composite scaffold for bone tissue engineering. At the first step pure and Mg-substituted hydroxyapatite (HA) (Ca10-xMgx(PO4) 6OH2) nano-hexagonal rods with 14–45 nmdiameter.for this, calcium nitrate, magnesium phosphate hydrate and potassium dihydrogenphosphate were used as precursors for Ca, Mg, and P, respectively. Calculated amounts of magnesium ions (Mg+2) especially from 0 to 8% (molar ratio) were incorporated as substituted into the calcium sol solution. Deionized water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH= 9.... 

In a solar central system plant about 40% of energy losses occurs in the heliostat field. Furtheremore, half of the investment costs for construction of the plant is related to the heliostat field. Therefore, an optimal design of the heliostat field is necessary for reduction of levelized cost of energy in solar tower power plants. In this study, in order to optimally design the heliostat field, first energy performance of the helistat field in one year is simulated. Solar power and sun’s position at each moment of the day is determined by mathematical relations. Then, loss factors in the field are modelled and heliostat field layout is designed by an algorithm. Finally, by using PSO... 

The power generation system of this type of power plants operates on the air flowing through the power plant’s chimney and colliding with the turbine blades within the chimney. When the solar collector warms the nearby air and thus expands the air by absorbing the sunlight, a difference is created in the density. Then, this difference in the density creates the phenomenon of buoyancy, making the air pass to the top of the chimney through the collector.This study simulated and optimized a solar chimney power plant. The simulation and optimization were performed based on the information of Manzanares Solar Chimney Power Plant in Spain (located in 150 km from the south of Madrid). It was... 

The issue under discussion in this paper is to optimize the fuel consumption of the Toyota Prius hybrid car. In order to solve this problem, the ADVISOR design model used by NREL in the Matlab / Simulink environment has been used. Various parts of this model are described. The optimization performed on this issue is based on the emotional controller. This controller works by simulating learning in animals based on encouraging and punishing them. With the introduction of the controller, the model and its inclusion in the fuel consumption control and its implementation have achieved good results. In the initial state and the controller in the model, the fuel consumption was 4.9 liters per 100... 

Today, due to the scarcity of fossil energy resources, security of energy supply, and increasing environmental concerns, we need to develop new technologies to promote energy-saving and reduce greenhouse gas emissions. One of the suitable options for this purpose is to use the simultaneous production of electric power, cooling, and heating. Meanwhile, trigeneration systems that provide part of their energy needs from the sun, due to the free solar energy source and low environmental impact, can be an ideal technology for clean and safe scattered production. The present study has suggested a trigeneration system of cooling, heating, and power generation based on the organic Rankin cycle and...