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Total 31 records
Geometric-Based Fault Diagnosis in a Grid-Connected Inverter
, Ph.D. Dissertation Sharif University of Technology ; Namvar, Mehrzad (Supervisor)
Abstract
Inverters are the main utility in transmitting power from distributed generation (DG) systems toward grid and their safe and immune performance has become a major concern among the system designers. In addition to poor power transmittance, faults in inverter can harm other equipment such as DG and local load. Consequently different protections has been considered to increase the reliability of these systems. Some of these protections like fuses and varistors are implemented in the hardware while others are considered in the processor. In the later class of protections, fault detection and isolation (FDI) system has been the subject of intense investigation in inverters over the past two...
Nonlinear Geometric Approach to Fault Detection in Mechanical Systems
, M.Sc. Thesis Sharif University of Technology ; Namvar, Mehrzad (Supervisor)
Abstract
The demand for safety operating systems is growing with the new developments in technology. One of the important and critical issues in system monitoring is the capability of the system to detect probable faults and hazards. In model-based fault detection one specific diagnostic signal called residual should be generated for each fault that is only sensitive to a particular fault and independent of other faults and disturbances. In this thesis we try to investigate the nonlinear geometric approach in fault detection of a class of mechanical systems. After a brief introduction to geometric tool for nonlinear inputaffine systems and conditions in which output is decoupled from input, we...
Identification and Control of Robot Manipulators using Cell Phone Sensors
, M.Sc. Thesis Sharif University of Technology ; Namvar, Mehrzad (Supervisor)
Abstract
The goal of controlling robot manipulators is to perform the mission intended for its end effector. Model-based control is a solution that can achieve the control goal with high speed and accuracy in the presence or absence of environmental obstacles by using the knowledge of the robot model. In this thesis, the Armtin 5 robot model parameters were identified in two steps. In the first step, the gravity and friction parameters and in the second step, the dynamic parameters were estimated. In the estimation of gravity and friction parameters, the non-linear behavior of friction causes the estimated parameters to be accompanied by a large amount of error. Estimation of the parameters was...
Design, Fabrication and Model-base Control of a Brachiation Robot with Flexible Support
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Gholamreza (Supervisor) ; Namvar, Mehrzad (Supervisor)
Abstract
Nowadays, many researches are inspired by nature and living creatures in order to build various scientific and industrial products such as robots, because of the highest level of creativity which is used in creating them along with their high level of efficiency in power consumption and designing parameters. Underactuated Robots are the type of robots which have more degrees of freedom comparing to the number of operators. As a result their optimum control has a lot of complications. Brachiating robots are designed and built based on an inspiration from long armed apes (Gibbons). This type of monkey is highly skilled in twisting in trees and traversing. This type of movement benefits from...
Design of Globally Convergent Observers for Robotic Systems
,
M.Sc. Thesis
Sharif University of Technology
;
Namvar, Mehrzad
(Supervisor)
;
Mobed, Mohammad
(Supervisor)
Abstract
In a typical rigid robot manipulator, joint angels and velocities are often considered as system states. Joint angels are usually measured by precise Shaft Encoders. However, lack of velocity measurement sensors “Tachometers” and their undesired characteristics in most of existing robotic systems make it difficult to have access to full system states. As full access to the system states in various applications is inevitable, velocity observers can be used to reconstruct or estimate the unmeasured velocity signals. This thesis presents an observer for global estimation of joint velocities in robot manipulators. A non-minimal model of a robotic manipulator is introduced to design an...
Robust Control Scheme for a Grid Connected DG System under Weak Grid Conditions
, M.Sc. Thesis Sharif University of Technology ; Namvar, Mehrzad (Supervisor) ; Karimi, Hoshang (Supervisor)
Abstract
Three-phase voltage source converter (VSC) is vastly utilized in the renewable energy resource and distributed generation (DG) systems interface units due to its high controllability and flexibility. Because of the high nonlinear nature of the system, the gird-connected inverter shows poor performance if the conventional control scheme are used. In this thesis, a new control scheme based on backstepping strategy is presented for control of a grid connected DG systems. The proposed scheme is responsible for regulating the active and reactive power components of the VSC power of the DG system. The VSC of the DG system is connected to a stiff utility grid through an L-type filter. In the first...
Implementation of Magnetic Angle Sensor (Contactless Potentiometer) in a Servo Control System
, M.Sc. Thesis Sharif University of Technology ; Pourmohammad Namvar, Mehrzad (Supervisor)
Abstract
The purpose of this research is to develop a contactless angular sensor based on magnetic methods that in addition to having similar outputs to resistive angle sensors (contact potentiometers) has advantages such as longer lifetime and no sensitivity to contamination, moisture and dust. In this research, an angular GMR sensor is designed and manufactured and tries to present a product that meets the required standards and can be sold in domestic and foreign markets
Real-Time Hand Pose Estimation Using Camera Vision System
, M.Sc. Thesis Sharif University of Technology ; Hashemi, Matin (Supervisor) ; Namvar, Mehrzad (Supervisor)
Abstract
Hand pose estimation is something that has applications in many fields, including augmented and virtual reality systems, as well as mixed reality. Hand gesture recognition and classification applications including sign language recognition and non-handheld senarios (such as storefront contactless Survey systems) that have found special cases in the Qovid-19 pandemic period Shows the highest hand pose estimation importance. In our work, we target 2D and 3D estimation at the same time and also use RGB camera as a sensor to record input data. It becomes more economical to achieve Compared with using RGBD or depth sensors . There is only one RGB image in our input. Also there is no contract to...
Customer Churn Prediction in Telecom Industry
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Saeed (Supervisor) ; Namvar, Mehrzad (Co-Supervisor)
Abstract
One of the important tasks of the customer relationship management of any company is to control the customer churn rate. Because according to research, retaining existing customers for a company costs less than attracting new customers. One of the most important tasks in order to control customer churn is to anticipate customers who intend to leave the company. This thesis proposes new method for customer churn prediction in mobile telecommunication industry. Mobile operators are structured in such a way that they can record and store a lot of data. In this dissertation, the most appropriate operator data was selected using data mining methods and various features related to customer churn...
Job Scheduling for Edge-Cloud Computing in IoT Systems
, M.Sc. Thesis Sharif University of Technology ; Shah Mansouri, Hamed (Supervisor) ; Namvar, Mehrzad (Co-Supervisor)
Abstract
IoT-based systems use cloud computing servers that are generally far away from them to perform tasks. Whenever there is a computational task that requires heavy and complex processing, the problem of offloading decision is to identify the best computing server to perform the processing related to this task. Numerous dynamic factors affect the solution to this problem.Optimization in energy consumption of the device that has generated a task alongside reducing its calculation delay can be applied in solving the offloading problem. The optimization problem that is formed to minimize the energy consumption in the offloading decision is an integer programming problem that is generally difficult...
Elimination of Signal Distortion Using Generative Adversarial Network
, M.Sc. Thesis Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor) ; Pour Mohammad Namvar, Mehrzad (Supervisor)
Abstract
Nowadays millions of images are shared on social media every day , So image inpainting has become an important issue . After advent of Generative adversarial network image inpainting methodes based on deep learning has been revived and significant progress has been made . For a proper image inpainting , The inpainted image must benefit from the appropriate structure and texture in the missing regions . Therefore, in this project , an attempt is made to use a two-stage structure by using Generative adversarial network .in first stage first by using Gabor filters , the image structure is extracted and then the image structure is completed , while the second stage focuses only on the...