Sharif Digital Repository

This project is providing appropriate software which could manage maintenance activities in a plant. All sections of the software have been designed in a way that can ease the management of maintenance activities. There are about 100 forms in the software that have been designed according to the forms which are being used in some Iranian cement plants and other maintenance software and also what we recognized important to be added or designed. One of the most important aspect of this software is the analytical section of the software where the user can get analytical reports from the software and based on the reports judge about the status of the plant and make new decisions in order to... 

In order to reduce damage caused by power outages on rare events that lead to long-term disconnection of microgrid from utility grid, isolated mode performance of microgrids including wind and hudro turbines with energy storage systems is considered in this study. Using wind energy as a renewable resource is considered as an appropriate choice for power production in microgrids. However, the uncertainty in wind turbines power generation is something challenging. The existence of water resources near the wind farms causes a special opportunity for operation of these resources along with wind turbines. This thesis aimed at balancing energy supply and demand in island mode of microgrid,... 

The analysis of electrical energy consumption parameters such as rate and amount of consumption, plays an important role in the planning of power systems. Because the dynamic analysis and evaluation of these parameters provides a detailed forecast of consumption and power system load. these forecasts is given to planners and engineers as the input of power system planning .Given that the electrical energy consumption system can be thought as a dynamic system, System Dynamics (SD) method would be very appropriate for modeling and analyzing its behavior. In this thesis, based on the SD and by means of dynamic loops, a comprehensive dynamic system for electrical energy is introduced. So the... 

The inevitable emergence of electric vehicles into the transportation industry in the near future can be a potential challenge or an opportunity for the power system. Vehicle-to-Grid can provide services for microgrids and the electricity market. The players of the game for participation of electric vehicles in microgrid or electricity market are vehicle owners, microgrid operators, and the aggregators. The formation and continuation of this interaction requires the interests of all institutions involved in the subject to be considered. Since there has not yet been an established conceptual or executive framework for the utilization of these vehicles in Vehicle-to-Grid idea considering... 

One of the most effective and robust algorithms in watermarking are additive and multiplicative methods. Although the detector of additive watermarking methods are easier than the multiplicative one, they do not gain from human visual or auditory systems. This is the main drawback of additive watermarking techniques. On the other hand, the most advantage of multiplicative watermarking methods is that the power of the watermark is proportional to the power of the host signal. In this thesis, we have introduced a new multiplicative watermarking technique for audio and image signals. For the audio signal, the embedding is performed on the wavelet coefficients. We used Maximum likelihood rule... 

Converting analog signal to digital one is one of the most important issues in signal processing which can be done by using analog to digital converter (A/D). In the first part of this thesis, sigma delta converters based on minimum support filter are investigated. Then, we will show that iterative algorithm can be used in order to improve the performance of the overall system significantly. Asynchronous converters can be utilized for the sake of decreasing power in the process of analog to digital converting. In these converters, a few numbers of samples will be taken from the regions which signal has high autocorrelation. In other words, samples in the asynchronous converters have more... 

In this thesis, detection problem in CDMA systems in overloaded regim is investigated. To thid end, both wireless and optical CDMA systems are considered. In overloaded CDMA systems, if the spreading matrix is invertible and channel is ideal and noiseless, then in the receiver the information of users can be detected without any error. Previusely, it was proven that for limited information symbols space, there are some matrices which are invertible or detecting. However, optimal receiver in these systems is comlex and infeasible. The only case that the optimal receiver can be implemented in a fesible way, is when the spreading matrix is constructed using kronecker technique. Therefore, in... 

Wireless communications often requires accurate knowledge of the underlying channel be­ tween transmitter and receiver which leads to channel estimation problem. Wireless chan­ nels are mostly multipath channels and have sparse impulse responses in time domain. One popular method in this field is to estimate the channel using training symbols. Also, Orthog­ onal Frequency Division Multiplexing (OFDM) and Multiple-Input Multiple-Output OFDM (MIMO-OFDM) systems are two popular and widely used systems. Since in training-based channel estimation methods some resources which can be utilized for data transmission is used for the channel estimation process, decreasing the number of pilots or... 

The remote sensing is the knowledge of gaining information about an event without having direct access to it, and synthetic aperture radars (SAR) have gained spectacular attention in this filed due to their wide applications and high efficiency. The performance of SAR, which are classified in the space-borne or space-borne radars is similar to that of pulse radars. The transmitted signals in SAR are generally chirp signals, and the received signal is two-dimensional which is scattered in two dimensions of range and azimuth called as raw data. Due to relative movement between the radar base and the target point, the distance between the radar base and the target point would not be fixed along... 

Anaerobic digestion of waste and wastewater has attracted researchers’ attention due to its important effect on reducing greenhouse gas emissions and reducing the level of environmental pollution and production of methane as a renewable energy source. This process is highly sensitive and can become unstable due to the presence of complex biochemical reactions and containing various types of chemical in it. In order to understand and improve the performance of this process, modeling and design of an appropriate control strategy is needed. ADM1 is the most accurate model for this process which is used in this study to describe and simulate the anaerobic reactor. Constrained and unconstrained... 

Anaerobic digestion of waste and wastewater has attracted researchers’ attention due to its important effect on reducing greenhouse gas emissions and reducing the level of environmental pollution and production of methane as a renewable energy source. This process is highly sensitive and can become unstable due to the presence of complex biochemical reactions and containing various types of chemical in it. In order to understand and improve the performance of this process, modeling and design of an appropriate control strategy is needed. ADM1 is the most accurate model for this process which is used in this study to describe and simulate the anaerobic reactor. Constrained and unconstrained... 

In restructured power system, the Independent System Operator (ISO) implements Security Constraint Unit Commitment (SCUC) for clearing of day-ahead market. In this project, SCUC is also uses for simultaneous clearing of energy and reserve market. Spinning reserve and of generating units and Interruptible Loads (IL) are considered as system operating reserves in the proposed model. Some of IL usage restrictions such as maximum load curtailed, maximum curtailment hour in a day, maximum length of each curtailment and etc is also considered. One of these constraints is interruption time (the time between ISO’s request and IL’s Answer) which is very difficult to formulate. Expected Energy Not... 

On one hand Code Devision Multiple Access (CDMA) as an efficient spread spectrum multiple access solution was under consideration in recent years. On the other hand one of the main challenges in cellular networks was near-far effect and fading effect which cause different received powers from different users.
In this thesis we are going to investigate near-far effects in overloaded CDMA systems from different aspects. Firstly we will investigate on the robust systems over near-far effect, propose near-far resistance codes and a very low complexity ML decoder for a subclass of these codes. Secondly we deal evaluation of the sum capacity of finite dimensional CDMA systems. These systems... 

The electric power industry is experiencing important changes brought about by the deregulation. Electric power generators and users engage in power transactions which take place over the transmission system and create losses. Transmission losses represent up to 1⎯5% of the total generation, and cost millions of dollars per year. Consequently, the problem of “who should pay for losses” arises and the satisfactory sharing of the transmission system utilization costs among all market participants has become a key issue. Unfortunately, losses are expressed as a nonlinear function of line flows, and it becomes almost impossible to calculate exactly the losses that are incurred by each generator,... 

The micro-scale channel creation in Osteochondral scaffolds is a prominent issue in tissue engineering. In this project we tried to identify the relevant parameters to obtain the method for injecting a biodegradable photo polymer to achieve a micro channel by predictable size.Due to inadequate accuracy in measuring the properties of the non –Newtonian working fluid, it was decided to use the Newtonian fluid equations in this study. The relevant equations for injecting the liquid under constant pressure were extracted. The modeling and design of micro syringe system was then completed. Using the made set up experiment to measure the fluid viscosity were performed.The next step was the... 

In order to reduce investment and operation costs of the power systems, transmission expansion planning is inevitable. In fact, transmission expansion planning is to determine when, where and how many lines need to be added to power system with a minimum of investment and operating costs. In this thesis, transmission expansion planning has been performed at uncertainty in generation and N-1 criterion condition where uncertainty in generation means uncertainty in the moment of adding power plant to power system. In previous studies, transmission expansion planning was performed with DC-load flow in which, the power loss and voltage profiles were ignored due to the approximation in the... 

The aim of this thesis is investigating the approaches proposed for controlling switched systems and designing a controller for MIMO switched systems. The system under consideration is in strict feedback form with unknown dynamics, unmodeled dynamics, state-dependent delays and disturbances and input nonlinearity (saturation, backlash, dead-zone). In this work, the unknown dynamics are estimated by an intelligent approximator. The arbitrary switching law is assumed and for control purpose the switching instances are not required. The backstepping technique has been utilize for controller design and by using a nonnegative switching function and a common lyapunov function, the closed loop... 

Due to advances of biotechnology, control of bioprocess has become very important. The goal of this project is to simulate the acetic acid production bioreactor and designing an adaptive PI controller for this reactor. For this goal, a suitable model has been selected from the literature and simulation has shown that the system has a nonlinear dynamical behavior. In order to control the system in a wide range of operating conditions, the adaptive PI controller was designed. In single input-single output case, the concentration of the product is controlled in such a way that the production rate is maximized, assuming that the pH and temperature are kept constant. Then a two input-two... 

Due to the successful experience gained in the process intensification and implementation of Reactive Distillation and Divided Wall Column in industry, Reactive Divided Wall Column have also been considered as a further step in process intensification. One important research area in implementation of RDWCs is their control issue. In the present study, the dynamic simulation of reactive divided wall columns and their control were studied and the adaptive model predictive control was used for the control objectives. Aspen Dynamics software was used for simulation and MATLAB software was utilized for applying the control strategy. The advantage of the applied control method is the use of... 

The “hypothalamus-pituitary-adrenal” axis is one of the most important axes of the human body, and cortisol is one of its key products, which plays an essential role in the immune system, stress management, and many diseases. Appropriate modeling and simulation of this axis can help us to understand how the body reacts to stress and inflammation, to examine relevant diseases, and how drugs affect the body. In this study, by combining an axial model of the hypothalamic-pituitary-adrenal axis with a model of adrenal cells, a bi-level model including several time delays has been developed that can predict the effect of stress on this axis. Some parameters of the model have been modified through...