Sharif Digital Repository

This thesis focuses on the design procedures of a Type Test tunnel intended to be used for performance verification of large electrical generator air to water coolers with a dimension of 3*3 meters. Using guidelines of related standards the tunnel was designed and modified to satisfy the requirements set by installation site and manufacturing limitations. As this required some deviations from standard guide lines, the correctness of the final design was evaluated using numerical computation of flow inside the tunnel. The tunnel structure and its internal parts were analyzed for strength and deflections. Using the results of numerical computations, the other main equipments of tunnel such... 

This project presents algorithms for intelligent control of the viral load in a HIV-1 infection model. The first part of thesis was dedicated to the study of the three states model adopted to describe the HIV-1 infection. A sensitivity analysis of the model parameters was described and computer simulations were provided to show the influence of the parameters explicitly. Then, an internal model control based on neural networks was implemented on the introduced infection model with including the RTIs and PIs drugs efficacies as control input. A stable adaptive neuro-control approach was presented for affine in the control nonlinear dynamical systems, whose nonlinearities were assumed to be... 

Vaccination is one of the ways of disease control and prevention, which not only protect individuals against the disease, but also reduce the disease spread rate. Mass vaccination of individuals is not always possible due to the high cost and limitation of immunization resources. Therefore, researchers are always seeking solutions to find the persons that their immunization may have a greater impact in reduction of disease spread rate. The advent of network epidemic models and the possibility of removal the secured nodes in those models, showed that this problem is equivalent to finding a limited set of individuals that their removal will eliminate or minimize the number of people at risk of... 

Edit distance or Levenshtein distance is one of the most fundamental problems in computer science and engineering to measure the dissimilarity between strings.This problem is solvable in O(n^2) time using dynamic programming and in 2015 it was conditionally proven that no truly subquadratic time algorithm (\textit{i.e.}, O(n^{2-ε})) exists for edit distance.Since 2001, approximating edit distance within a constant factor was recognized as one of the biggest unsolved problems in the field of combinatorial pattern matching.This thesis designs seven approximation algorithms for edit distance and its related problems.Firstly, two quantum approximation algorithms are designed with constant... 

Three-phase electronic loads are used to test the performance of various electrical devices such as power supplies, generators, and transformers. Conventional electronic loads are composed of passive components that consume the energy, so have low power density and efficiency and to manage the produced heat, massive cooling systems are required. Nowadays, to increase efficiency and power density, three-phase regenerative electronic AC loads have been developed. To return energy to the grid and control the input power factor, the structure of these loads is based on back-to-back converters. In this project, a 35 kVA three-phase regenerative electronic AC load is designed. To control the power... 

The main objective of this project is to take the first step in designing torsional vibration damper (TVD) for engines in Iran. To this end a complete dynamic model of a 4 cylinder internal combustion engine comprising of all reciprocating parts plus the crankshaft was developed using Bond Graph method. Real firing data of the engine was used as input to the system and output torque to gearbox shaft as the output. The system equations in two cases, with TVD and without TVD were derived. MATLAB software was used to solve these equations in finding the quality of performance of the torsional vibration damper. Dynamic properties of crankshaft and designed TVD were obtained using finite element... 

There is an effective and functional connectivity between the central nervous system and the cardiovascular system, which is controlled by the autonomic nervous system. Investigating this connectivity and its direction can provide valuable insights into their functioning. To examine causal and directional relationships, EEG and ECG signals, which contain useful information about the activities of these two systems, are utilized. Granger causality is a popular method for estimating effective linear connectivity. However, the assumption of linearity in effective connectivity is not always valid, as nonlinear interactions also exist between the nervous and cardiovascular systems. Estimating... 

The conventional bearing-only tracking solutions are based on Kalman filter. Whenever the problem equations are nonlinear, Extended Kalman Filter (EKF) or more complicated methods are used necessarily. However, EKF suffers of being biased and unstable. Here a new recursive method based on a linear modeling of the problem is proposed, the method does not need an initial guess and outperforms the Kalman filter in the terms of accuracy, complexity and stability. Furthermore, input information needed for the proposed tracking filter is just the observer position, time and value of each angle measurements and the computation load is less than even a simple EKF. mathematical analysis, as well as... 

In this work, Hough detector has been compared with optimum detectors. We consider 2-D range-time data space, which is constructed by storing the radar returns from different range cells during several successive scans. In this space, target trajectory can be modeled as a straight line for short time intervals, and can be extracted by applying Hough transform transcendentally. In this work, a new detection method based on the likelihood ratio in the data space with Gaussian noise is introduced. ALR and GLR processors have been designed. Then formulas for probability of detection and false alarm rate is calculated, and verified via simulations. A new criterion for estimation quality is... 

Why firms does not submit several steps in their bids curve? In this paper, we present a mathematical model for the behavior of power plants in a Pay-as-Bid auction market. According to this model, in the case that the power plant has a fixed marginal cost, the optimal behavior for him is to offer only one price, but in the case of linear marginal cost, bidding one price is not an optimal price, and with increasing the slope of this function, the number of steps and their price level will increase. We also show that increasing the level of competition in the market will force the plants to lower the price level and the number of steps. The model of this paper also predicts the factors... 

Communication Buoys are devices that facilitate radio communication between underwater ships and surface stations. In this research such device is thoroughly designed for a submersible application. The system comprises of buoy, connection cable, buoy cavity, cable passage, winch and other supporting and safety subsystems. Buoy and cable system was analyzed in a general form and their stable states were determined for different ship maneuvers, sea streams, and wave conditions. Based on this, optimum buoy geometry and cable length were found for the defined application and other subsystems were detail designed. To evaluate the design, some of the system components were manufactured and... 

Cars with high center of gravity, such as SUV-Sport Utility Vehicles- have high tendency to roll over in high speeds and rapid maneuvers. An idea formerly proposed is to use a high speed rotating disc like a gyroscope on the onset of the rollover to exert a high stabilizing moment on the vehicle, and consequently prevent rollovers. Also using two counter rotating discs with opposite nutation will prevent interference with the car other degrees of freedom. To reduce the interference of the spinning discs with the vehicle dynamics, the discs are to be brought to speed by the action of a high accelerating mechanism during the rollover process(similar to the action of an airbag). This project...