Sharif Digital Repository

In this project, multi objective optimization (MOO) approach is used to optimize the SOFC/MGT integrated system performance in two strategies. In order to improve the performance and increase of Micro Gas Turbine (MGT) efficiency, it can be combined with Solid Oxide Fuel Cell (SOFC) which it has high operating temperature.The multi-objective optimisation method used allows to generate Pareto curves that represent the trade-off between conflicting thermo-economic objectives of SOFC/MGT integrated system, like, electrical efficiency, output power and electricity cost. The results of the thermo-economic optimization offer a basis for decision making and engineering improvement. SOFC capacity... 

Considering high potential of solar energy and exhaustibility of fossil fuels in Iran, using solar energy seems to be inevitable. But one of the main problems in the application of these systems is high investment and maintenance costs. So, in this thesis, suitable solution is presented for decreasing cost and optimizing of a solar absorption refrigerator based on developed energy model. This system consists of two CPC solar collectors and a thermal energy storage system using phase change materials that provides input energy to the generator of absorption refrigerator. The exergy efficiency of system components is calculated by relations of energy model and exergy analysis. Then... 

Micro combined heat and power (MCHP) system is one of the most worldwide considered energy saving with high total efficiency systems. This research presents the application of MCHP to small scale users such as residential or light commercial buildings. Initially, the available technology in micro scale that can be used as an energy generator has been specified and categorized. Since then, by using the overall energy purchased cost by households assuming the energy carriers are kerosene, gas and electricity, total demand has been determined considering that the electricity expenses showing the use of electric appliances and the gas expenses expressing the cost of domestic hot water and... 

In this research, the aerial load transportation in the urban environment by cooperative quadrotors is investigated. This system requires two sub-systems: path planning and control. The path planning subsystem designs the payload's path and at the same time determines the shape of the flight formation of agents in order to be able to carry the payload. The design of the path-formation is done in the presence of constraints such as the collision avoidance with obstacles, inter-collision avoidance to each other, the collision avoidance of the slung load with the obstacles and the minimum and maximum allowable cables' forces. Therefore, the shape of the formation flight is determined... 

The vortex tube is a simple device that injects compressed gas (air) tangentially into the vortex chamber through one or more injection nozzles. After entering, the flow becomes rotational and an axial cold flow goes towards the cold outlet and a peripheral hot flow goes towards the hot outlet. Besides all the different applications of the vortex tube, the main application of this device is cooling. Here, the goal is to optimize the geometry and physical conditions to improve the performance, which is done by using a commercial software and numerical analysis of a vortex tube to understand the flow physics and optimization. In this research, we use experimental and numerical data for... 

In this thesis, a method is presented for improving the observability of the heading angle in a UAV when using the Visual-Inertial navigation algorithm MSCKF by adding a magnetometer sensor. The proposed algorithm serves as a complementary extension to the primary algorithm, and efforts have been made to seamlessly integrate the magnetometer sensor into the primary algorithm to allow for easy modifications to the sensor's characteristics and to observe the resulting output in system simulations. Improving the observability of the heading angle will lead to an enhancement in the overall system state estimation. To achieve this, a new update stage is added to the existing algorithm.... 

In this research, a cooperative terminal guidance algorithm has been derived for simultaneous multi-interceptor collision with a target. This algorithm is obtained using the combination of model predictive control method and differential game theory. One of the features of this method is the calculation of the optimal guidance command in the form of an explicit relationship. Another feature of this method is its resistance to disturbances due to the use of differential game theory. The first innovation of this research is the use of this hybrid method to create a guidance algorithm, even in the non-cooperative guidance problem. The next innovation is in creating a cooperative terminal... 

In recent years, the country's electricity industry has faced many problems. On the one hand, the number of consumers and the intensity of their consumption have increased, and on the other hand, the production sector has been facing many problems. Since the management of these systems requires the development of mathematical models, the introduction of various operational indices and system analysis, in order to provide solutions to reduce consumption, increase production and reduce environmental damage, in this research Bistoon Kermanshah steam power plant, as a selected power plant, is simulated in both design and operational conditions, by the information available in the design... 

Radial turbines with small dimensions and in small power capacities are of great interest. In general, turbine performance improvement and higher output power may be achieved through increasing the inlet mass flow rates however at the expense of more weight and larger dimensions. On the other hand, increasing the inlet total temperature to the turbine will result in higher power potentials. Nevertheless, the turbine needs to be cooled in case that the intended inlet temperature goes beyond the turbine material limitation. In this thesis, radial turbine equations are reviewed and the logic of a 1D algorithm is developed where parameters like the total temperature, total pressure, and mass... 

The present study investigates the effect of MR materials on the vibrations of three-layer pretwisted rotating beams. For this purpose, by considering MR material as the core of the rotating beam and using Hamilton's principle, the equations governing the three-layer rotating beam are extracted. After solving the desired equation, we optimize the dynamic behavior of the three-layer beam at different rotational speeds. Using the Genetic Algorithm optimization tool, the desired beam weight will be minimized and maximum damping will be applied to the desired system. The goal is to find the optimum magnetic field strength for maximum damping in the system at any rotational speed, in addition to... 

Due to well mechanical properties and high resistance to environmental conditions, metal pipes are used to transport oil and gas products, water and sewage, as well as hydraulic systems in aircraft or aerospace systems. Therefore, maintenance of oil and gas transmission lines in energy-related industries and pressurized tanks in the aviation industry has always been a concern of engineers. Due to the problems of old methods for repairing damaged pipelines or aerial structures, it seems necessary to provide new, safe and cheap methods for repairing them. Various engineering standards for pipelines and their repairs have been presented so far which have analytical solutions to determine the... 

This thesis is about multidisciplinary design optimization of MRI ¬controlled robots with a nonlinear model approach in the cardiovascular system and simulates its behavior to reach cancer cells. Such robots, designed to perform medical procedures with minimal side effects to the patient, include a set of ferromagnetic nanoparticles attached to the polymer and disposable drugs such as cancer drugs.The disciplines considered in this issue include structure, hydrodynamics, propulsion, controllability, and trajectory. The proposed model in this study, in addition to the main forces acting on the robot such as magnetic force, hydrodynamics, and apparent weight, also examines other forces due to... 

Billions of dollars are spent annually repairing broken or damaged pipes and fittings. The bulk of these costs relate to traditional methods used to repair and rehabilitate pipelines, such as replacing the desired part or using steel sleeves on the damaged part, this operation requires shutting down the service, which is costly. Uncertainty about the reliability and durability of existing repair methods has created the need to develop and provide a fast, safe, economical and safe way to repair pipelines and fittings. This need has been met by using the capabilities and potentials of composites, and composites have replaced traditional methods that reduce costs and time. In this project, the... 

The current research is devoted to the design and optimization of a Blended Wing Body aircraft configuration in the conceptual design phase. In this respect, two objective functions with eight design variables have been considered within the optimization process in order to reach to a desired design. The key objective functions include the aerodynamic efficiency as well as the aircraft empty weight alongside the longitudinal stability requirement that are accounted for within the Genetic algorithm optimization loop. In this regard, some analytical and semi-empirical relations are utilized to determine the aerodynamic and structural characteristics of different designs alongside the numerical... 

In this article, guidance and control of reusable launch vehicle at terminal phase has been studied. The goal of this article is increasing the accuracy and safety of the guidance and control system of the launch vehicle in order to successfully land on ground surface. Integrated guidance and control, being a novel method in guidance and control, is used to guide the launch vehicle in the re-entry phase and landing phase on ground surface. The returning object studied is a Falcon 9 rocket for which we find the 6 DOF model. The landing method of this vehicle is vertical. Implementing an integrated guidance and control system is a novel approach in this area. The controller used in this... 

For complex systems, it is difficult to obtain an accurate model of system dynamics using physical laws. Therefore, one of the most common solutions is to use system identification techniques. Flapping wings are one of the most challenging systems in the engineering world. In this study, we use a fuzzy wavelet neural network to identify time periodic flapping wing systems. In order to extract network’s input and output information, we use analytical simulation using MATLAB software. After validating the input and output information of the system with the help of the ADAMS software, the identification process of the flapping wing system is performed in longitudinal and lateral-directional... 

The purpose of the current study is to design an optimal trajectory and control for an aircraft to perform a microgravity maneuver automatically. This subject is by itself an important research topic that has not yet been attempted via optimal control formulation and modelling. Space stations are commonly utilized to conduct long-term microgravity research. Unfortunately utility of space stations to perform space based microgravity experiments is expensive and inaccessible for many researchers and scientific institutions. However, since many experiments requiring microgravity conditions can be performed in short time intervals, there is a possibility to meet their demand via optimal... 

One of the most important issues among defense is the increasing of the defense power using present facilities. Therefore, optimal setting and arrangement of equipment by considering different air-to-earth attack of enemy without knowing of properties and capabilities of available systems may not be possible. So, using defense equipment considering properties of them, and paying attention to existence restrictions and effective elements can have an effective role with the design of suitable algorithm.The main purposes of this thesis are: maximization of the efficiency of a defense system against. aerial invader targets, achieving the best arrangement of defense equipment based on suggested... 

The purpose of this thesis is to provide a basic design or a design tailored to the specific requirements of a particular repository. In recent years there has been a great deal of research on composite tanks and many articles have been published in this regard. But these papers have mostly focused on design without an overview of system design and merely with an optimization perspective using different algorithms. For this purpose, the research will use a axiomatic design method that allows the designer to design with a systematic perspective without the need to use optimization algorithms. This method has shown that by applying the principles governing that end product properly, it will... 

In this study, novel algorithms are presented for nonlinear parameter varying systems with uncertainty in the model predictive control using heuristic algorithms. To this end, some algorithms are developed which provide the possibility of estimating simultaneously states and control signal of the stochastic nonlinear systems. Then, the model predictive control algorithm is presented for stochastic nonlinear systems with uncertainty to estimate uncertainty and compensate it using ant colony optimization. Next, the model predictive control algorithm is developed for nonlinear system with matched bounded uncertainty using particle swarm optimization. Performance of the developed controllers is...