Sharif Digital Repository

Due to the simplicity and generality, design of feedback control systems in the frequency domain is among the most prominent topics in the control systems engineering. The problem of compensation means properly adjusting the loop frequency response at critical frequencies. Considering the point that the traditional methods usually use trial and error procedures for compensation, analytical design of fixed-structure controllers for exactly adjusting such values has great importance. Benefitting from the capability of fractional-order dynamics, the compensation problem is studied from three aspects in this thesis. At first according to the importance of adjusting the system frequency response... 

One of the subsets of the radar systems is recognition of targets. Radar Target Recognition (RTR) is a process in which a target is distinguished from a set of targets. To recognize radar targets, we need to extract useful information from the returned signal from them. The most important issues in recognizing radar targets are the selection of information that reduces the amount of information needed for the identification process, the ease of extracting information from the moving target, and the ease of decision making to determine the identity of the target. One method is to produce a high resolution range profile, which is the one-dimensional image of the target in the direction of... 

In cases with excessive anteversion even after adolescence, surgeons have to choose osteotomy surgery to modify this abnormality. This surgery and modifying the anatomical problem does not necessarily lead to modify the patients’ gait cycle abnormalities; the authors’ hypothesis is the probable reason may be the persistence of the implement of the patients’ kinematics compensation mechanism even after the surgery. This mechanism is used to almost correct the gait of those with excessive anteversion. First, by using gait analysis text books, a patient’s gait cycle is analyzed; this analysis is consist of 3DGA with EMG and observational gait. Then, by using OpenSim, the patient’s patterns of... 

n this article, we find necessary conditions for the existence of Ito Integral in a Banach space with respect to compensated Poisson random measure (cPrm). Ito integrals with values on M-type 2 Banach spaces F of the above form exist for all measurable, adapted functions f square integrable w.r.t. β ⊗ d t (f ∈ M2T;_(E/F)),with β being Lévy measure associated with cPrm, and have strong second moments. We show that, for general separable Banach spaces F, an inequality of the type resulting for M-type 2 Banach spaces with constant depending on cPrm is necessary and sufficient for the existence of Ito integral having second moment finite for all f ∈ M2 T;_(E/F). It is shown that M2 T;_(E/F) is... 

There are a wide variety of light-triggered switches. Photoconductive semiconductor switches (PCSSs) have been investigated intensively for many applications owing to their unique advantages over other switches. The advantages of PCSSs make them a perfect choice for many important applications where high switching accuracy and high-power capability are required. Photoconductive switches are fabricated from a variety of semiconductors, including silicon carbide (SiC), gallium arsenide (GaAs) and gallium nitride (GaN). In Photoconductive semiconductor switches (PCSSs) the switching mechanism is initiated by optical illumination and laser source controls the flow of current. In the off or... 

In this thesis, we model and analyze coherent optical OFDM systems which are highly concerned as future fiber optic communication. To this end, we first introduce various applications of that in optical communication systems and investigate its probes and cones. In the rest of the thesis, we characterize the mathematical structure of the nonlinear phase noise and discuss the previous methods of compensation of that and propose some new ways of nonlinear phase noise compensation and equalization. And as we discuss each method we also investigate its computational complexity and BER performance. We propose three new phase noise compensation method, considering optical phase conjugation, we... 

The wide-area damping controller (WADC) has been proposed to enhance the damping of inter-area oscillations. The most challenging deficiencies to make this controller practical are the power system operating condition changes and the inherent time delay of remote signals. They can deteriorate the controller performance and the whole system stability if not properly accounted for in the design procedure. This thesis presents an adaptive delay compensator (ADC) on the basis of the latest development in the wide-area measurement system (WAMS) to cater to varying latencies. The proposed compensator can effectively reciprocate the phase deviation resulting from varying delays to improve the... 

Magnetic bearings have been used in industry to achieve an acceptable performance, high precision and vibration suppression of rotating machinery in recent decades.The absence of physical contact between the bearing and rotating components provides access to high rotational speeds which is a problem in conventional bearings.In addition, capabilities such as stiffness and damping adjustment can be used to reduce the harmonic vibrations caused by mass unbalance. The unbalance compensation is one of the main topicswhich has attracted the attention of many researchers in the field of rotordynamics. The aim of this thesis is to design and fabricatea three-pole active magnetic bearing test rig and... 

In this study, I examine the role of board composition and ownership structure and trading days on board compensation of 156 Iranian non-financial public firms. Regarding board composition, I find that board size, CEO-Directorship, and the presence of busy directors positively explain board bonus. Concerning ownership structure, results reveal that outside block-holders and the percentage of individual investors negatively influence on board bonus. Also, trading days is proved to have a positive impact on board bonus. Furthermore, I examine the impact of compensation relating to board composition and ownership structure and trading days (predicted compensation) on the future operating... 

One of the problems in vessels is the marine oscillations that occur due to the collision of sea waves with the vessel. These oscillations in small yachts can cause passengers to seasick upside down and overturn objects in the boat, or in industrial ships can cause problems in the operation of cranes on vessel, and in military vessels can cause errors in targeting weapons and radar systems. The purpose of this research is to design and simulate a robotic compensating table that can actively compensate the vessel fluctuations by using control algorithms in three directions of Roll, Pitch and Heave and create a level that can be used in Medium-sized boats were used to eliminate harmful... 

With the recent developments in power electronics and electrical drives, there is a need for precise position sensors today more than ever. Having high precision and high reliability in harsh environments, resolvers are the most preferred position sensors among other types of prevalent position detectors. In order to control linear machines, which are widely used in different industries, linear resolvers are employed. This project aims to propose a structure for tubular variable reluctance resolvers, formulate an analytical model for and optimize the proposed structure. In addition to having an acceptable precision, the proposed model should be less time-consuming compared with finite... 

In many industries, including oil and gas industries, power plants, refineries, petrochemicals, steel and cement industries, industrial complexes and consumer industries, there are tanks for storing materials. It is necessary to measure level of products while they are stored in tanks of different sizes. Ultrasonic is one of the non-contact and accurate measurement technologies that can provide a suitable solution for liquid tank monitoring. The purpose of this thesis is to design and build the electronic parts (transmitter and receiver circuits) of an ultrasonic system that is capable of detecting levels at a distance of less than 5 meters with an accuracy of 0.5 % full scale. In this...