Sharif Digital Repository

Concerns like fuel cost, pollution and global warming has made it necessary to look for new energy solutions. Renewable and alternative energies have proven themselves to be helpful in this matter. Renewable energy(RE) is the energy that comes from natural resources such as sunlight, wind, rain, tides, waves and geothermal heat, which are naturally replenished at a constant rate. Renewable energies are environmentally friendly, not cheap at the beginning but naturally available in a constant rate and wide spread, unlike fossil fuels that are localized in the limited places. In this thesis in order to generate environmental friendly power we consider two renewable energy resources: wind and... 

Due to the increasing consumption of fuel, the use of new methods with high efficiency to remove sulfur from fossil fuels is felt more than ever. Hydrogenation and oxidation of sulfur organic matter, such as thiophenes, is an old method of desulfurization of liquid fuels. Using a photocatalyst, everything can be done in an environment that is very low cost. In this study, the photocatalytic elimination of dibenzothiophene was investigated. For this purpose, carbon-doped thiamine dioxide was used as the photocatalytic base, which is synthesized by hydrothermal method. This method is the same source of titanium and carbon. To increase the performance of the catalyst, platinum metal was loaded... 

Capturing the atmospheric CO2 and turning it into value added products is a topic that has been extensively studied in recent years. One of the methods through which CO2 is valorized is via converting it into carbon nanofiber, CNFs. CNFs can be an important material in future human activities due to its valuable properties such as wide range of electrical conductivity, their superior flexibility and strength, But it is currently obstructed in use due to the high cost of manufacturing and the complexity of the synthesis. Furthermore, in today's world, human life is heavily influenced by greenhouse gases, and avoiding emitting gases like CO2, is almost infeasible. This thesis provides an... 

On account of the exhausting nature and increasing daily cost of the fossil fuels, it seems that replacing the fossil fuels by an alternative source of energy is inevitable. Moreover, in the remote areas that the electricity network is not accessible, the use of distributed sources (DSs) such as solar energy and wind energy is advantageous. Continuity of the supply and voltage control of the load in spite of the stochastic nature of the generated power of the renewable energy resources are the main concerns in the distributed generation (DG) systems. In this thesis, stand-alone operation of a DG unit comprising a solar unit and wind turbine as primary sources of energy is considered. A... 

High efficiency and low-emission fuel cells have the capacity to replace fossil fuels for energy supply concerns. Solid oxide fuel cells operate in relatively high temperature and have power plant applications. Hence, they are acquainted to be coupled with cycle gas turbine to reduce the cost and increase the overall system efficiency. The control of these hybrid systems is so important. Due to the system nonlinearity and having more than one controlled variable, its control with classic methods would be difficult. The model based predictive control is used as an alternative to mitigate these difficulties. In addition to their high performance, their extension to the multivariate case would... 

The application of fuel cell systems as sources of clean energy production is common. Control, performance optimization, design, manufacturing and the operation management are considered as significant research interest of the fuel cell in academic circles. A major problem, at least in the advanced model-based control, is the slowness of solving the nonlinear multi-scale model (time). One option would be using the black-box neuro-fuzzy models. Then if the predictive controller is used for this distributed system, calling the output of neuro-fuzzy model allocated a negligibility proportion in time of calculations during the optimization. In this project, the data generated by a dynamic... 

In recent years, fuel cells have been proposed as an alternative option to conventional energy conversion systems. Fuel cell is an electrochemical system that can convert chemical energy to electrical energy without combustion. High efficiency, low temperature performance, poor pollution, good reliability, flexibility in the production potential, low start-up time and high life expectancy are the major advantages of this system. The most important barriers to the use of fuel cells are high cost polymer membrane and using expensive platinum catalysts. Modeling of fuel cells in general will meet two objectives. The first, due to the complexity of the processes taking place within the cell,... 

Modeling and Controlling of a satellites fuel slosh is considered a vital problem in the field of satellite attitude control. In this paper modeling and control of the attitude of a satellite carrying a partially filled spherical fuel tank, which uses the diaphragm as a propellant management device (PMD), has been studied. The fuel slosh dynamics is modeled using a spherical pendulum with two degrees of freedom and a rigid arm, which represents the first mode of sloshing. The effects of the diaphragm that surround the fuel surface, are considered as torsional springs and dampers attached to the satellite body. The combined dynamics equations of the satellite rigid motion and the fuel slosh... 

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... 

Nowdays, distributed generation (DG) systems based on renewable energy sources have significantly increased around the world as an alternative solution to enhance the power quality and reliability and reduce the need for extensive transmission system as well. An evolved recent concept called microgrid is developed by grouping a cluster of loads and DG units in a common local area which increases the integaration of sustainable energy generation systems. This thesis presents control of a medium voltage (MV) microgrid considering multi-hybrid distributed generation systems (MHGS) and renewable energy resources in island mode. The first part is focused on the development a control strategy for... 

Molten carbonate fuel cell (MCFC) is a kind of high operating temperature fuel cells (600-800℃), tupically used for stationary power plant. These fuel cells have high efficiency (about 50%), but expensive to produce electricity. Hence, fuel cells are integrated into gas turbine cycle to decrease cost and increase efficiency of system. In this work, an integrated pressurized molten carbonate fuel cell is selected. Then, structure of selected process is changed and two new systems have proposed. Then, steady-state and dynamic behaviors of three systems were simulated separately, and their performances were compared. Efficiency increased about 5% in two new structures. Total power of system,... 

Fuel cells are considered as one of the most promising for production of efficient and low-polluting electrical power. Hence, they can be a suitable alternative for fossil fuel sources. The solid oxide fuel cell (SOFC) is a direct conversion process, which works at high operating temperature (about 1000 °C). This high operating temperature makes them suitable for combining with gas turbines to achieve high overall fuel and power efficiency. A hybrid comportment consisting of an SOFC and a turbine (GT) is a multivariable nonlinear and strongly coupled system. On the other hand, total power generation in these systems which is a principal parameter should not be so sensitive to operating... 

In the late 1980s, the International Maritime Organization started working on reducing air pollution by ships, and the result was the approval of Annex 6 of MARPOL and its mandatory implementation since 2005. Since then, due to the increasing importance of pollutant emissions in the maritime transport industry and the stricter regulations of the International Maritime Organization and the high cost of fuel for ships, ship owners are looking for ways to reduce fuel consumption. For this purpose, various activities related to reducing the fuel consumption of ships were carried out. Among these, the use of energy saving devices can be a solution. Recently, the hull vane, as a fixed underwater... 

Nowadays, the attempts to reduce fuel consumption, greenhouse gas emissions and atmospheric pollutants, and economic savings, besides alignment with new rules, have been become the top priorities in the marines industry. In order to satisfy these goals, many efforts have been undertaken, including the vessel's trim and draft optimization which has done both experimentally and numerically and also thrust system simulation, to set a logical link between the effects of trim and draft of the ship and the calculated value of the required thrust from simulation to be able to optimize the fuel consumption. In this method, the ship is considered at the specific draft and the trim in bow and stern... 

UAV routing algorithms, correct modeling of battery life is very important, which can be done by dynamically integrating the UAV with routing. A drone must visit a set of targets, although after reaching a predetermined distance from the target, the drone must adjust its flight mode for loading (delivery) and after delivery must complete the escape maneuver. And prepare for the next delivery. Routing and optimization factors should be combined to ensure the safety of the vehicle and the feasibility (route feasibility). Research and studies that have been done in this field, have solved the problems by considering the exact time and also less attention to the energy limitations of these... 

One of the methods to enhance the economic performance and safety factor of nuclear power plants is to determine a suitable fuel loading strategy in a reactor core. Different methods have been already elaborated to choose the proper fuel loading pattern. Selection of the best pattern for fuel loading ensures the best use of fissile material and more safety during reactor operation. Perturbation theory method is one the methods which could be used to solve this kind of problems. The effect of non-uniform perturbations on the reactor operation can be evaluated by multigroup calculations and using proper space dependent group constants. In this study, a C# based program is developed to find the... 

this is one of the most widely used is the weighted residual method. The advantages of this method is likely to reach an appropriate solution is (in this project collocation method for solving systems of differential equations is used). After solving steady-state model with the lowest number of variables come to turn the control measures, including non-linear design of a Kalman Filter incentives that could be the orthogonal modulation system (which requires less computational time and good accuracy) as a representative of the system in the state estimation, optimization and control system used. In the end, offering a range of control methods such as multivariate linear and nonlinear... 

Gas turbine engine control is a demanding task that requires the regulation of the thrust as well as the satisfaction of the limitations such as engine aerodynamic instability, over temperature and over speed. Fuzzy logic is an attractive technique for the control of poor understood unmodeled, or complex systems especially where the experience of human operators is available to provide qualitative rules. In such cases, it has been found that control decisions can be made on the basis of linguistic measures or fuzzy algorithms. The controller that is designed on the basis of this theory is called fuzzy logic controller. The main objective of this thesis is hardware implementation of fuzzy... 

This study invewstigates the performance of a coupled microfluidic microbial fuel cell-microbial electrolysis cell producing biohydrogen in presence of shewanella oneidensis MR-1 from excreted oxalate of human metabolic processes. The effect of different parameters such as cell geometry including spiral and straight microchannels, precipitation of nano-particles on anode surface, substrate flowrate and the number of microfluidic microbial fuel cell supporting required power for microbial electrolysis cell were assessed. By anode modification, the maximum current density of 428 W m-3 was obtained which is less than 6-fold of the maximum power density in the cell fabricated by zinc foil. The... 

Because of the high operating temperature, interconnect surface tends to be oxidized and Cr2O3 oxide layer will be created on the surface. This phenomenon is undesirable due to decreasing electrical conductivity, so a preservative coating is needed to improve the interconnect properties. In this paper, a dense perovskite thin film was successfully synthesized on a ferritic stainless steel (type 430) substrate by a sol-gel dip coating method. This coating improved chemical stability, oxidation behavior of the substrate and decreased cathode poisoning. The lanthanum chromite was coated on the substrate by sol-gel dip coating process. First, during a hydrolyze process, a stable sol was made up...