Position Error of Resolver in a Closed Loop Control

, M.Sc. Thesis Sharif University of Technology Khajueezadeh Ravari, Mohammad Sadegh (Author) ; Nasiri Gheidari, Zahra (Supervisor)

Abstract

Permanent Magnet Synchronous Motors (PMSMs) are more conventional and widely employed in Electric Vehicles (EVs) applications. The rotor position performed an essential role through PMSMs drive; therefore, any deviation in the detected position will be evaded in coordinate transformations, originating from external or inherence sources. Subsequently, the discussed faults will be conducted to three-phase currents and output torque through erroneous transformations. Resolver’s estimated rotor position due to fault occurrence will be defined as aggregating ideal and non-ideal components. Moreover, based on inherence periodic in resolvers’ principle, non-ideal components could be written by the...

Measurement of Radionuclide Transport Parameters for Soil Samples Taken from Naein Radioactive Waste Disposal Site by Using Column Experiment and Determining the Concentration Profile through the Column

, M.Sc. Thesis Sharif University of Technology Poursharifi Ravari, Mohadese (Author) ; Samadfaam, Mohammad (Supervisor)

Abstract

Radioactive wastes are generated at different stages of the nuclear fuel cycle and other activities related to the handling of the radioactive substances. In order to protect human being and the environment from any harmful effects of ionizing radiation, it’s necessary to isolate radioactive waste by disposing them in near surface or deep geological formations (depending on the radioactive hazard). To ensure that the waste is properly isolated from the environment for required periods of time, the safety assessment of the disposal site is essential. Transport of radionuclides from the disposal site to the environment is the essential part at any safety assessment program. Therefore,...

Broadcast Efficient Verifiable Secret Sharing

, M.Sc. Thesis Sharif University of Technology Hosseini Beghayi Ravari, Amir (Author) ; Izadi, Mohammad (Supervisor)

Abstract

Verifiable secret sharing (VSS) is one of the basic problems in the theory of distributed cryptography and has important role in secure multi-party computation. In this case, it is tried to share a confidential data as secret, between multiple nodes in a distributed system, in the presence of an active adversary that can destroy a number of nodes, such that the secret can be reconstructed with the participation of certain size of honest nodes. There are two types of active adversary; Static and dynamic which the latter can change it’s corrupted nodes among the protocol. VSS protocols have different types of algorithmic complexity and one of these definitions, is the use of broadcast channel...

Content Based Community Extraction in Social Networks from Stream Data

, M.Sc. Thesis Sharif University of Technology Sadegh, Mohammad Mehdi (Author) ; Abolhassani, Hassan (Supervisor)

Abstract

Increasing in social communication via electronic ways has been made social network analysis of these communications more important each day. One of the most important aspects in social network analysis is community detection in such networks. There are many different ways to extract communities from social graph structure which in some of them the content of communication between actors has been noticed in community extraction algorithm. In this thesis after a short survey over advantages and disadvantages of existing methods for community detection, a new method for extracting communities from social networks has been suggested which in addition to streaming property of data it spot the...

Numerical Modeling of Turbine Flow Meter and Improving its Performance Using CFD

, M.Sc. Thesis Sharif University of Technology Dadkhah, Amir Hossein (Author) ; Karimi, Mohammad Sadegh (Supervisor)

Abstract

Studying the performance of flow meters is of great importance in order to improve their quality. In this study, we are looking for an optimal design for a turbine flow meter in which the measurement accuracy, pressure drop and response speed indices are improved. For this purpose, a turbine flow meter with a diameter of 2 inches has been selected and its performance has been numerically modeled using computational fluid dynamics in a steady and transient state. By modeling the steady state, the measurement accuracy and pressure drop indices are obtained, and by modeling the transient state, the response time of the flow meter is obtained. In order to increase the accuracy of numerical...

Numerical Investigation of the Effect of Cooling Layout Manufacturing Tolerances on the Thermal Field of a Nozzle Guide Vane

, M.Sc. Thesis Sharif University of Technology Bafandkar, Mohammad Reza (Author) ; Farhanieh, Bijan (Supervisor) ; Karimi, Mohammad Sadegh (Supervisor)

Abstract

One way to increase the efficiency and improve the performance of a gas turbine is to increase the inlet gas temperature. On the other hand, the inlet temperature has an allowable operating range, and increasing it beyond the tolerance of the alloys used in turbine blades causes structural defects and significantly reduces the blade life. Therefore, to increase the blade life, various cooling methods such as internal and layer cooling are used. Considering the blade geometry and cooling paths, accuracy in the manufacturing process is doubly important in the production of these blades. The importance of this issue is that if the cooling channels produced are inconsistent with the design...

Structure Formation and Galactic Dynamics in Modified Gravity (MOG)

, Ph.D. Dissertation Sharif University of Technology Vakili, Hajar (Author) ; Rahvar, Sohrab (Supervisor) ; Mohammad Movahed, Sadegh (Co-Advisor)

Abstract

The standard model of Cosmology (SM), based on Einstein’s theory of general relativity (GR), is the best model in describing the cosmic-scale observations. In galactic scales, however, galactic dynamics show a discrepancy between the observed luminous mass and the predicted value from the theory. Two approaches are suggested to eliminate this inconsistency: assuming the existence of dark matter within the context of GR, or modifying the theory of gravity in galactic scales, like MOND or MOG. In this thesis, we study the spherical collapse and the formation of shell galaxies in MOG, in comparison with SM. We introduce the action and the field equations of MOG and the equation of motion of a...

Axial Flux Resolver Versus Radial Flux One From Fault Tolerability Point of View

, Article IEEE Sensors Journal ; Volume 23, Issue 17 , 2023 , Pages 19176-19183 ; 1530437X (ISSN) Khajueezadeh, M. S ; Tootoonchian, F ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2023

Abstract

Reliability and fault tolerability of the resolvers, as the first-choice rotor angle sensor in permanent magnet synchronous motors (PMSMs), are big concerns. Among the resolver categories, the assessment of axial and radial flux resolvers over each other is an interesting subject, which will serve as a guideline for engineering society. On the other hand, resolver errors will significantly degrade the drive system and primary motor operating conditions, injecting more stress into the motor. Therefore, it is clear that the resolver's faulty conditions can lead to thermal changes in PMSM, which shows the connection between the frequency of resolver faults and the heat level of the motor frame....

Developing a very fast and accurate model of linear sinusoidal area resolver considering end effects and faulty conditions

, Article IEEE Sensors Journal ; Volume 23, Issue 18 , 2023 , Pages 21147-21154 ; 1530437X (ISSN) Khajueezadeh, M. S ; Tootoonchian, F ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2023

Abstract

Similar to each electromagnetic device, resolvers' design and performance investigation through an accurate and preferably fast tool are necessary. On the other hand, due to the 3-D geometry of the sinusoidal area (SA) linear resolver, its performance evaluation and iterative design procedure is a big challenge, especially through 3-D time-stepping finite element analysis (3D-TSFEA) and common analytical methods. Accordingly, the following study suggests a hybrid linear resolver model to overcome the above challenges. The suggested hybrid linear model can precisely consider the longitudinal end effect and faulty resolver conditions. In addition, implementing the suggested hybrid model in...

The Dependence Structure of Negatively Dependence Measures

, Ph.D. Dissertation Sharif University of Technology Barzegar, Milad (Author) ; Alishahi, Kasra (Supervisor) ; Zamani, Mohammad Sadegh (Co-Supervisor)

Abstract

Strongly Rayleigh measures are an important class of negatively dependent (repulsive) probability measures. These measures are defined via a geometric condition, called “real stability”, on their generating polynomials, and have interesting probabilistic properties. On one important property of negatively dependent measures is their rigid dependence structure. In other words, the it is impossible for these measures to have strong overall dependencies. In this thesis, we study two manifestations if this phenomenon: (1) paving property and (2) tail triviality. Informally, the paving property states that it is possible to partition the set of the components of every strongly Rayleigh random...

Essays In Iranian Wholesale Electricity Market

, Ph.D. Dissertation Sharif University of Technology Mardani, Hassan (Author) ; Fatemi Ardestani, Farshad (Supervisor) ; Ghazizadeh, Mohammad Sadegh (Supervisor)

Abstract

In this thesis, consider three important questions in the Iranian Wholesale Electricity Market (IWEM) and answer its. The first one is whether the bidding behavior of the firms in the IWEM has been ex-post optimal? The results of the research show that, on average, the firm’s bidding behavior didn’t optimal in the IWEM, and therefore the bidding strategy of them could be improved. This issue is importance from the regulatory viewpoint in terms of assessing market efficiency and market power of firms, as well as from the firm’s point of view to improve the bidding strategy and increase its profits. The second issue is the assessment of the firm’s ability to exercise unilateral market power by...

Control and Optimization of Office Building Air Conditioning System Taking Into Account Dynamics of Energy Demand, Ambient Indoor and Outdoor Air Quality and Indoor Air Quality Standards

, M.Sc. Thesis Sharif University of Technology Khamisabadi, Zahra (Author) ; Khajehpour, Hossein (Supervisor) ; Hassanvand, Mohammad Sadegh (Co-Supervisor)

Abstract

Office buildings, as one of the largest energy consumers in the building sector, play a significant role in national energy consumption. Given the importance of energy optimization in achieving sustainable development, reducing energy consumption in these buildings not only lowers costs but also helps preserve natural resources and mitigate environmental impacts. In this regard, providing energy optimization solutions, improving efficiency, and revising operational patterns play a key role in reducing energy consumption and ensuring user comfort. On the other hand, attention to indoor air quality is equally critical, as polluted indoor air can negatively affect the health and productivity of...

Development of a hybrid reference model for performance evaluation of resolvers

, Article IEEE Transactions on Instrumentation and Measurement ; Volume 70 , 2021 ; 00189456 (ISSN) Khajueezadeh, M ; Saneie, H ; Nasiri Gheidari, Z ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2021

Abstract

Resolver is an electromagnetic position sensor typically used in the closed-loop control of permanent magnet synchronous motors (PMSMs). In terms of structure and principle of operation, resolvers are very similar to electrical machines. In this regard, different numerical and analytical models have been developed for the performance prediction of a resolver, with a compromise between computational burden and accuracy. Therefore, a fast and accurate hybrid model of the resolver is presented in this article, which can be used for resolvers with different structures. Additionally, this model can easily be implemented in software such as MATLAB/SIMULINK. The performance of different variable...

Reliability Analysis of Two Resolver Configurations Under Faulty Conditions in 2DOF System

, Article IEEE Transactions on Instrumentation and Measurement ; Volume 72 , 2023 ; 00189456 (ISSN) Khajueezadeh, M ; Zare, F ; Nasiri Gheidari, Z ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2023

Abstract

The existence of resolvers in the two degree of freedom (2DOF) control algorithm is mandatory due to their improved performance in harsh environments. However, resolver's errors significantly influence the control system's stability. Therefore, it is required to comprehensively investigate the resolver's reliability under fault conditions. In this regard, an employed assessment model is presented. Subsequently, the failure modes in the 2DOF and one degree of freedom (1DOF) resolvers' configurations are investigated thoroughly. Among the methods used to assess reliability, the Markov model is chosen for the reliability analyses. After meeting all of the above, the faulty conditions are...

Effecive & efficient DSM configuration guidelines for low-cost development of complex systems

, Article Gain Competitive Advantage by Managing Complexity - Proceedings of the 14th International Dependency and Structure Modelling Conference, DSM 2012, 13 September 2012 through 14 September 2012 ; 2012 , Pages 125-137 ; 9783446433540 (ISBN) Sadegh, M. B ; Sharif University of Technology

Institution of Engineering Designers 2012

Abstract

With the proliferation of more complex systems has come the need to find better solutions in both technical and management domains. Such complex systems are usually larger in size, have more parallel operations and contain more complex interfaces (Eisner, 2005). The Design Structure Matrix is a very useful tool in handling such complexities, provided that the system designer can use it properly. This paper addresses how effectiveness & efficiency are defined for a DSM and how these two important characteristics can be achieved. The importance of understanding the solution space in constructing an effective & efficient DSM is discussed and general guidelines are given on configuring the DSM...

Choosing the Optimal Assembly Angle of Multi-Part Elastic Rotor Components with the Aim of Passing Critical Speeds

, M.Sc. Thesis Sharif University of Technology Ghamari, Mohammad Amin (Author) ; Dehghani Firouzabadi, Ruhollah (Supervisor) ; Amirzadegan, Sadegh (Co-Supervisor)

Abstract

Multi-part rotating parts are used in various industries with very high revolutions. Therefore, the method of assembling each part and keeping the axis of rotation of each part close to the axis passing through two supports (bearings) is important. In this research, three main steps are followed, the development of the differential equations governing the multi-part rotating system and the calculation of the range of oscillations created at the critical points, and then the calculation of the optimal assembly angles with the aim of reducing the introduced oscillations, and finally the discussion of crossing the speeds A crisis is being investigated. The method of obtaining the system of...

Investigating Distributed Denial of Service Attacks on MQTT Protocol And Proposal of New Attack Scenarios

, M.Sc. Thesis Sharif University of Technology Sadegh Esfahani, Hatef (Author) ; Aref, Mohammad Reza (Supervisor) ; Salmasizadeh, Mahmoud (Co-Supervisor)

Abstract

MQTT (Message Queuing Telemetry Transport) is one of the essential and widely used protocols in the Internet of Things (IoT) networks. It operates at the application layer (Layer 7) for data transmission. As IoT applications using this protocol for communication have grown, securing such systems against security attacks has become a significant challenge. One of the important attacks implementable by IoT networks is Distributed Denial of Service (DDoS) attacks. In this thesis, we initially provide a general overview of IoT security and demonstrate how DDoS attacks disrupt the availability feature in these networks. We then examine known types of DDoS attacks to gain a better understanding of...

Optical Conductivity of Fermi Arc States

, M.Sc. Thesis Sharif University of Technology Hamidi Ravari, Zeinab (Author) ; Jafari, Akbar (Supervisor)

Abstract

Recently, some materials, such as Weyl and Dirac semimetals, have been found in condensed matter physics whose band structure behaves like Weyl fermions of elementary particles near some points of the first Birillouin zone. The Weyl equation that governs these materials, have boundary because they are finite. By applying proper boundary conditions, two-dimensional surface states have been emerged. these states are called fermi arc sates because the surface corresponding to the fermi energy is not a closed surface. Surface states are mixed with bulk states because by getting close to the end of fermi arcs, surface states tend to bulk states con-tinuously. Being able to distinguish between...

Fabrication of Composite Scaffold Composed of Cartilage Extracellular Matrix/Chitosan with High Mechanical Strength for Cartilage Tissue Engineering

, M.Sc. Thesis Sharif University of Technology Khozaei Ravari, Mojtaba (Author) ; Mashayekhan, Shohreh (Supervisor) ; Baghban Eslami Nejad, Mohammad Reza (Supervisor)

Abstract

Methods that has been used for articular defects are faced with many limitations, so new therapies based on tissue engineering were taken into consideration in recent years. However, tissue engineering also encounters challenges regarding optimal scaffold construction and suitable cell source selection. Mature harvested chondrocytes are limited in number and may lose their chondrogenic potential in several cultures, leading to dedifferentiation. In addition, using stem cells also presents unique challenges associated with them, among which hypertrophic differentiation is the most substantial problem. Choosing the appropriate biomaterial similar to the cartilage structure with sufficient...

A high-accuracy two-stage deep learning-based resolver to digital converter

, Article 13th Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2022, 1 February 2022 through 3 February 2022 ; 2022 , Pages 71-75 ; 9781665420433 (ISBN) Khajueezadeh, M. S ; Emadaleslami, M ; Nasiri Gheidari, Z ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2022

Abstract

High-efficiency Permanent Magnet Synchronous Motors (PMSMs) are widely used in industrial applications. Subsequently, resolvers as position sensors experience increasing usage in the drive of PMSMs. Measuring the rotor's position using a resolver needs a costly Resolver to Digital Converter (RDC). Therefore, in this paper, a software-based, low-cost RDC is presented against the conventional Angle Tracking Observers (ATOs). The proposed RDC is a high-Accuracy two-stage Deep Neural Network (DNN)-based one. In this regard, an overview of the resolvers' function and the general methodology to DNN training is given. Then, the case study is done on the gathered data from the set of the resolver...