Sharif Digital Repository

Statistics is an essential part of decision making and management in all organizations if the needed information is correct and updated. Due to lack of suitable information systems, it needs rework and spend extra time to gather information. Information Technology is used to summarize organizational information. It supports management of organization to make decision for strategic planning, tactical planning and operational programming by creation, storage, retrieve and distribute correct information to managers. For implementing these systems, there are many solutions. Selecting each one depends on conditions and potentials. Implementing integrated systems is expensive task therefore large... 

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,... 

Integrated SOFC plants, because of the high efficiency and optimum energy consumption, are important processes that have many applications. According to the importance of these plants, their optimum operability and favorable operations are also very important. One of the ways to optimize the process performance is the suitable selection of the control structures. The objective of this project is to analyze the operability or inherent controllability of integrated SOFC plants in the absence of any controller. In this work, the controllability of the process have been investigated with using the output controllability index and the other indexes such as relative gain array, singular value and... 

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 this research, we consider an assemble-to-order production system which accepts order for multi-products. Demand is stochastic and price-dependent. We also consider a sale index that links demand of each period to the previous periods demand. The variety of products which use common parts makes this revenue management system complicated. Furthermore, since the price of each product can have an effect on other products demand, it causes price dependency among them. We model the problem within the framework of dynamic programming approach to maximize discounted profit of the firm during a finite and multi-period horizon. We develop an integrated system of pricing and production decisions... 

In this research, we consider a made-to-order production system which receives orders for a single product. The demand is stochastic and price-dependent. We also consider a sale index that links the demand of each period to the demands as well as to the quality of the previous periods. The variety of quality levels and its effect on the amount of orders make this revenue management complicated. Furthermore, the price of each product is related to its quality and sales index. Furthermore, reference price causes the model to be significantly more complicated. We model the problem within the framework of dynamic programming approach to maximize the discounted profit of the firm during a... 

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... 

High-integrity systems are critical, complex software-controlled systems in contexts where the occurrence of failure can severely affect the environment, organization, and/or society. Examples are typically found among safety- critical and mission-critical systems. Typical high-integrity systems are highly hardware-dependant; hence, the rapid rate of hardware technology evolution in these systems demands the development of software systems that keep up with the hardware infrastructure. This necessitates the existence of elaborate software development methodologies which accommodate the volatility of the environment, and properly address the critical features required of the system under... 

This thesis is concerned with the robust control of multiple integrator systems, subjected to input saturation and external disturbance. Since nested saturation method has been demonstrated to be an effective tool for control of a chain of integrators, a feedback law using nested saturation is proposed. In order to deal with disturbance, an extended state observer is applied to nested saturation controller and a comprehensive analysis of stability is also presented. The existence of constant parameters in the proposed controller makes the design conservative which results in performance degradation in some cases at the presence of disturbance. To overcome this issue, an adaptive approach... 

In recent years, the issue of sustainability in the energy systems has attracted the attention of energy researchers. Using fossil fuels in common energy conversion systems cause environmental pollution, declining reserves of fossil resources and increase their prices because of the scarcity of fossil resources. Therefore, achieving the goals of sustainability necessitate using high efficiency energy conversion technology. Bio-inspired energy systems are one of the main candidates to improve energy conversion systems. The main target of this study is developing an optimal multi-generation energy system model, dynamically. MFC, Septic tank and Algae culture are integrated and produced power,... 

This thesis is related to the identification and design of a robust controller for an electrohydrodynamic printer system. As an emerging technology, this printer uses a strong electric field to deliver fluid ink from various conductive materials to the substrate. Modeling this system is complex due to the effect of different variables on its performance. In this project, first a simplified model with numerical solution data of the COMSOL model that is validated experimentaly is proposed. Then, by presenting a new control method that is a variant of an active disturbance rejection control baesd on extended state observer has been controlled. The new control method is actually an amendment to... 

Due to increasing population and economic growth that has improved the living standards of human societies, the resources of the three sectors of water, energy, and food are in short supply. The close connection between these three parts requires integrated policy-making. In this research, for an integrated water, energy, and food system, an integer linear programming model has been developed for the optimal selection of technologies, their capacity, and their water and energy flow. Agricultural development policies include the construction of greenhouses and the use of renewable energy technologies and wastewater treatment technology to supply energy and water to the domestic and... 

The purpose of the current study is developing an evaluation model for the electrical grid. Resilience is an approach toward risk management against disorders and protecting the system during critical conditions. The importance of resilience assessment, especially in crucial infrastructures, has always been at the center of attention. Nonetheless, previous studies in this field were mostly limited to micro-scales, meaning that only a limited part of the system was evaluated. Therefore, such studies rely on technical data and system details. This issue renders macro-scale assessments challenging. Some of the models, which are based on analytical-statistical methods, examine the systems at... 

Multi-vector energy (MVE) networks are one of the most complex systems which are attractive to many researchers. In this work, an integrated gas-power transmission network as an MVE network has been studied. The MVE benchmark used in this work comprises a gas transmission network, which is the core of the MVE, a power transmission network, and a Syn-Gas plant. The gas transmission network supplies the gas demands of its consumers. The main objective of this thesis is to design appropriate controllers to maintain the states of the gas network in its desired condition. Since the gas network is distributed parameter system and its model is an infinite dimensional state space, it is either... 

Automatic image annotation is an image retrieval mechanism to extract relative semantic tags from visual contents. The number of digital images uploaded in the virtual world is rapidly growing every day. Most of those images are not assigned with proper tags or labels. Although automatic image annotation methods are developed to assign proper tags to images, most of these methods assign some irrelevant tags and also sometimes a few relevant tags are missing. So far, the improvements of accuracy in newly developed automatic image annotation methods have been about one or two percent in F1-score compared to the previous methods. To reach much better performance, we analyzed most of the...