Sharif Digital Repository

Swaying is an unfavorable phenomenon in moving suspended loads. So, cranes are usually equipped by anti-sway controllers. In this thesis, various controllers have been applied to a prototype of gantry crane system with various control inputs, and their competency has been assessed. First, a 2-DOF model has been introduced. This model contains a trolley and double pendulum with variable length attached to it. Then, it has verified by two approaches: first is comparing with simplified equations of model with flexible cable; and second is comparing with behavior of simulated system by Visual Nastran software. Next, a SISO linear controller has been designed for container cranes and applied to... 

Hard real-time embedded systems often operate in harsh environmental conditions that necessitate fault tolerant computing techniques. These embedded systems are also energy-constrained, since energy consumption is one of the key objectives. Examples include satellites, surveillance systems, autonomous seaborne and airborne systems. Generally, fault tolerance is obtained by hardware or time redundancy in these systems. Checkpointing with rollback recovery which employs time redundancy is one of the common techniques for tolerating transient faults in real-time embedded systems. Using checkpointing in energy constrained hard real-time systems should be carefully employed. In this thesis, we... 

Image retrieval, simply put, is the process of finding images in a predefined set , that are similar to an image specified by the user. In particular, the user inputs an image as query, and expects to see images similar to the query. Our purpose is to retrieve the images, by means of visual features, without any use of latent information such as tags and annotations.Afer the first round of retrieval, the answers can become more accurate, by means of user feedbacks. In this state, using active learning methods may be usefull. By using active data selection, we hope to achieve the answer faster. Learning based on manifold assumption, is another means which may be used in image retrieval.... 

User cooperation is an important concept in wireless networks to achieve best performance subject to low cost. Dynamic and broadcast natures of wireless networks are two indispensable characteristics of these networks. Therefore, when a user transmits his signal to the receiver, other users in his neighborhood may receive the signal as well. Hence, these neighbors can decide to cooperate with each other in transmitting their messages to the receiver. On the other hand, due to the dynamic nature of the wireless networks, one can assume that each user has some knowledge about the interference signals or the fading coefficient that are not known to the other users. Therefore by utilizing user... 

In this study, the two rigid body modelling of a Coanda air vehicle (one rigid includes rotor and propeller and the second rigid includes the other parts of it) has been developed using Newton’s and Euler’s laws, and its motion was simulated in climb and forward flight conditions. Air vehicle propulsion force and moment have been modelled by employing the blade element momentum theory. In order to model the forces acting on the air vehicle, the drag force has been estimated by the results of analytical and computational fluid dynamics methods for the case of climb flight and by using experimental data of a cylindrical body for the forward flight. For modelling the control surfaces of this... 

The existence of motor synergies in motor system as a tool for reducing degrees of freedom has been always debated. In the last two decades some experiments in vertebrates show the existence of motor primitives in spinal cord. In additional by recording electromyogram from frog some regular patterns have been shown. Recently, a motor coordination model based on stochastic optimal feedback control has extracted synergies by mathematical formulation. In addition, according to this model synergies are the optimal solution of the problem and not for simplifying it. However, this model is investigated in linear dynamics. In this thesis, first, an inverse method for extracting synergies is... 

The mathematical analysis of the kidney has always been considered due to its complex performance. It’s about two decades that mathematicians work on the mathematical modeling of this tissue. Since Glomerular filtration of blood in the kidney has been regarded by physiologists for many years, they can access only to the qualitative data. Mathematicians can solve this problem by numerical modeling. In this research, an engineering model is presented for the analysis of this capillary network by investigating in the different scientific fields such as, physiology, medicine, computer science and mathematics. There are two major renal autoregulatory mechanisms, the myogenic response and the... 

One of the ultimate goals in robotics is to design autonomous robots. Among other things, this means a robot has to be able to plan its own motion. To be able to plan a motion, a robot must have some knowledge about the environment in which it is moving. Some of this information can be provided by a floor plan. For other information the robot will have to rely on its sensors. In this thesis, we consider that the environment is unknown for the robot. So, the robot uses weak sensor to planning its motion. The sensor can distinguish between colors. The robot can follow the colors. Therefore, we need to specify the umber of colors in which the robot can navigate by them. We propose an efficient... 

Chemotherapy is a proven and effective systematic approach to treat various types of cancers. Despite its advantages, chemotherapy would kill healthy as well as cancer cells. To overcome this problem, different controlling strategies are implemented. This study aims to provide a medicine drug delivery schedule for chemotherapy (by designing a proper controlling system) based on the verifiable mathematical models. First, the dynamic model is analysed and stability points are reviewed. The selected model has five state variables and two inputs. In this study, the focus is on dynamic model analysis and obtaining an effective and appropriate treatment pattern by designing a proper controller. To... 

Distributed feedback dye lasers are among the suitable candidates for spectroscopic applications due to their capability of producing widely tunable picosecond pulses in UV-IR region. However, the pulsewidth sensitivity of the laser to pump intensity fluctuations hinders its suitability for precision applications. In this thesis, by utilizing widely used Self Q-Switching model, we showed that if the dye solution is pumped by a narrow (sub-nanosecond) pulse, the laser can operates in the single-pulse output mode with a better stability over a wide range of pump intensity. After that, we used a dynamical model based on the induced polarization and Maxwell equations, where the obtained results... 

Reservoir Computing is a novel computing paradigm that uses a nonlinear recurrent dynamical system to carry out information processing. Recent electronic and optoelectronic Reservoir Computers based on an architecture with a single nonlinear node and a delay loop have shown performance on standardized tasks comparable to state-of-the-art digital implementations. Here we report an all-optical implementation of a Reservoir Computer, made of off-the-shelf components for optical telecommunications. It uses a semiconductor optical amplifier as nonlinearity, and a Fabry-Perot Resonator as a key element to establish the virtual nodes, connecting them and consequently, build the virtual neural... 

Removing SAW filter from the input of a receiver makes the receiver extremely vulnerable to all sorts of blockers and interferers. It is shown in this thesis that due to existing large out-of-band blockers the linearity of the saw-less receiver has to be considerably higher than that of the conventional receivers with input SAW filter. These ever-present and unwanted signals that show up in the absence of the input SAW filter are divided into two groups of far and near out-of-band blockers and interferers. It is shown that removing these groups of unwanted signals require two distinct approaches, one for near and the other for the far out-of-band blockers. An inclusive solution to protect... 

This research has dedicated to study the control of chaos when the system dynamics is unknown and there are some limitations on measuring states. There are many chaotic systems with these features occurring in many biological, economical and mechanical systems. The usual chaos control methods do not have the ability to present a systematic control method for these kinds of systems. To fulfill these strict conditions we have employed Takens embedding theory which guarantees the preservation of topological characteristics of the chaotic attractor under an embedding named "Takens transformation". Takens transformation just needs time series of one of the measurable states. This transformation... 

In this study, adaptive control of HIV infection was investigated based on feedback linearization. First, three state model of HIV infection was simplified to implement the adaptive approaches by using some assumptions. Then, adaptive control method based on feedback linearization was implemented on reduced order and three states infection dynamic model with including the RTIs and PIs drugs effects as control input. The parameter projection method, adaptive nonlinear observer and dynamic anti-windup were employed in implementation of adaptive control method to prevent singularity problem, to estimate system states and to avoid windup problem of external PID controller, respectively. Finally,... 

The following thesis is concerned with the effect of channel feedback in tracking and stability of linear Gaussian systems over Additive White Gaussian Noise (AWGN) channel when the decoder is the Kalman filter and encoder is the innovation encoder. When the feedback channel is described by a noisy link or a random switch, it is shown that stability is not possible for unstable systems. But for stable systems, an innovation encoder, Kalman filter decoder and a certainly equivalent controller for tracking and stability are presented. When the feedback channel is described by a deterministic switch, for both stable and unstable systems, an innovation encoder, Kalman filter decoder and a... 

global warming and air pollution due to the excessive consumption of fossil fuels have led to the proliferation of renewable energy sources (RESs). RESs are connected to the grid through power electronic converters and therefore, provide insignificant inertia and damping property for the system. As a result, the system overall inertia and damping is decreased and therefore, the system stability is jeopardized. This thesis presents a comprehensive small signal model for a virtual synchronous generator (VSG) integrated into a microgrid. In the developed state space, active and reactive power control loops of the VSG as well as resistances and reactances of the lines are considered. Based on... 

Feedback-seeking behavior is the effort of employees to get feedback from the environment and around people about their performance. One of the research questions in this field is about the factors that increase this behavior in the staff. Transformational leadership as a leadership style, stimulates, and motivates followers to achieving desirable operational results. In addition, an important consequence of this style could be increasing the followers' capabilities. Transformational leaders are trying to empower their followers to build and empower them, which can provide a strong incentive for employees to move and grow, which may encourage them to have a better performance. One of... 

In this thesis, chaotification of dynamic systems in general and chaotification via full state linear feedback are investigated particularly. Studying chaotification is a problem over investigating dynamics of chaos and controlling it, so studying this problem needs to have some general information about chaos and its dynamics. Because, this is a new case, researches in this field are not enough and actually, there is no paper on application of chaotification. Reviewing literature in this field shows that in solving problems of chaotification, there is no notice on applications and ability to apply it on physical systems. So one of the most important aims of this thesis, is to find an... 

In this thesis, a chaotic chemical process has been studied and a control method has been proposed. To do this, a reactor in which two autocatalytic reactions take place in parallel has been modeled. The catalyst decay has been considered as a separate reaction. The reactor dynamic is chaotic for a set of parameter values. In this thesis, dynamic behavior of this chaotic reactor has been analyzed. The main objective is to control the product concentration and a state feedback controller based on the process linearized model has been proposed. The suggested controller possesses integral action on desired concentration to eliminate control offset. Since concentration measurement is difficult... 

Degradation of signal to noise ratio (SNR) in today's low voltage circuits has been a challenging problem for analogue circuit designing. This problem is produced due to supply voltage reduction and noise level consistency in today's analogue circuits. Great efforts have been done in literatures for noise reduction in some analogue circuits, like low noise amplifiers, but there is no general method for noise reduction in active filters and introduction of a general method for noise reduction in active filters which are in vast usage in all analogue circuits, has always been demanded by circuit designers. In this project, a general method for noise reduction in active RC filters is introduced...