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Design and Fabrication of Frequency Scanning Antenna for Millimeter-wave Imaging in Ka-band
, M.Sc. Thesis Sharif University of Technology ; Farzaneh, Forouhar (Supervisor) ; Fakharzadeh, Mohammad (Co-Advisor)
Abstract
Millimeter-wave imaging is used in a vast applications like security, medical and non-destrcutive testings. Frequency scanning antenna is one of the optimum solution in mm-wave imaging systems, because of its accuracy, agility and low cost. In this method, changing the frequency plays the main role and leads the main beam to scan the space. In this thesis, by observing different frequency scanning structures, like microstrip antenna, slotted waveguide antenna array, substrate integrated waveguide leaky-wave antenna, different structures are designed and simulated. The antenna, which results in the best performance for an imaging system is selected for fabrication and measurement. The...
Travelling-wave Ka-band frequency scanning Antennas for millimeter-wave imaging applications
, Article 2016 8th International Symposium on Telecommunications, IST 2016, 27 September 2016 through 29 September 2016 ; 2017 , Pages 591-595 ; 9781509034345 (ISBN) ; Fakharzadeh, M ; Farzaneh, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
In this paper, a novel travelling-wave printed Frequency Scanning Antenna (FSA), which can be used for imaging purposes, is proposed. All sample designs scan the space symmetrically about the broadside direction. For different scanning ranges, two low profile antennas are designed on a 6.6 mils thick Rogers 4350 board substrate layer. Impedance bandwidth of the first one covers 6.5GHz, from 29.5GHz to 36GHz, and this antenna scans 56° in angular space. The second antenna has 5.6GHz bandwidth from 30.6GHz to 36.2GHz, and scans 98° in angular space by means of switching the input port. The average gain and the Side-lobe level (SLL) of the first and the second antennas are 11.46dBi, 12.8dB, and...
Coupling reduction of printed yagi antenna arrays for millimeter-wave imaging applications
, Article 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, APSURSI 2019, 7 July 2019 through 12 July 2019 ; 2019 , Pages 1767-1768 ; 9781728106922 (ISBN) ; Fakharzadeh, M ; Ranjbar Naeini, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, methods for reduction of coupling between receiving and transmitting antenna arrays are proposed and tested. Coupling between RX and TX causes saturation and a higher noise level in IF. So, coupling reduction improves image quality of system. Antenna element of arrays are printed antipodal Yagi-Uda antenna with greater than 8 dBi gain and higher than 4 GHz bandwidth. Frequency bandwidth of this imaging system is 27 to 30.5 GHz. Half power beamwidth of this antenna element is larger than 90 dB. Front to back ratio of this antenna is improved in this paper to 30 dB at 29 GHz. © 2019 IEEE
Ka-band frequency scanning antenna with wide-angle span
, Article Journal of Infrared, Millimeter, and Terahertz Waves ; Volume 40, Issue 2 , 2019 , Pages 231-246 ; 18666892 (ISSN) ; Fakharzadeh, M ; Farzaneh, F ; Sharif University of Technology
Springer New York LLC
2019
Abstract
This paper describes the design procedure and measurement results of a single-layer low-cost, and wideband frequency scanning antenna, which exhibits a nearly symmetrical beam-steering around broadside direction. The measured antenna bandwidth ranges from 27.5 to 40 GHz, which covers most of the Ka-band. In addition, the antenna main beam scans from − 52° to + 42° as the frequency sweeps from 27.5 to 36.5 GHz, showing 94° beam-steering range. At the center frequency of 32 GHz, the beam points to the broadside direction. The measured radiation patterns verify that the beam-pointing error is less than 2° over the scanning range. Furthermore, the measured gain for a 10-cell structure with 6-cm...
Improving Text-Video Retrieval Models using Language Models
, M.Sc. Thesis Sharif University of Technology ; Rabiee, Hamid Reza (Supervisor)
Abstract
Models specifically designed for images are widely used in various video understanding tasks, including text-to-video retrieval. For this purpose, videos are viewed as sequences of frames. Most models uniformly select a few frames from each video and pass them to the image-specific model. While simple, this method often results in the selection of repetitive or irrelevant frames. Several trainable frame samplers have been introduced, but none can select important and diverse frames. In this study, we propose a teacher-student pipeline for training a frame sampler tailored for the text-to-video retrieval task. In this pipeline, frame-to-frame and frame-to-description similarities obtained by...
Synthesis of Composite Coating with HA Nanoparticles on Ti by AC Plasma Electrolyte Oxidation
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
In this project, a ceramic biocompatible coating was applied on Titanium which is included Hydroxyapatite by AC Plasma Electrolyte Oxidation method. First, coating was performed in 5 different solutions and various duration in 500mA/Cm2 as a current density. Then, by microscopic and macroscopic images and size of porosity and also thickness of coat, 3 solutions were chosen for adding nanoparticles: Solution 1 which includes NaH2PO4 and Ca(CH3COO)2 , Solution 3 which includes Ca(CH3COO)2 and Na-Beta G and Solution 4 which includes Ca(H2PO4)2, HMP, NA2(EDTA) and Ca(CH3COO)2 . Also the time 10 minutes was chose as a appropriate time. The average of the porosities size in solution 1 was about...
Evaluating the Energy Consumption of Fault-Tolerance Mechanisms In Processors Implemented on Sram-Based Fpgas
, M.Sc. Thesis Sharif University of Technology ; Ejlali, Alireza (Supervisor)
Abstract
With growing interest in the use of SRAM-based FPGAs in space and other radiation environments, there is a greater need for efficient and effective fault-tolerant design techniques specific to FPGAs. The soft errors vulnerability of SRAM-based FPGAs limits their usage in safety-critical applications. Moreover, the rate of multiple soft errors increases due to the feature size reduction. Hence, this issue becomes a challenge against reliability of the implemented circuit on SRAM-based FPGAs. Appealing to specifics such as low cost and re-configurability in SRAM based FPGAs provide this ability to change implemented design remotely. This advantage is not negligible in safety critical...
Synthesis and Characterization of Praseodymium Nickelate for Low Temperature Solid Oxide Fuel Cell Cathode
, M.Sc. Thesis Sharif University of Technology ; Faghihi Sani, Mohammad Ali (Supervisor)
Abstract
Solid oxide fuel cells as high temperature electrochemical devices draw much attention in the last decades due to their fuel flexibility, high efficiency and low pollution. However, lowering operating temperature from about 850°C to around 650°C without significant overpotential loss, in order to lower costs and increase cells life time has remained a challenge. Recently, a new family of mixed ionic and electronic conducting ceramics (MIECs) which are formulated Ln2NiO4+δ (Ln= La,Nd,Pr) and crystallized in Ruddlesden–Popper structure, have been regarded as appropriate cathode materials for the low or intermediate temperature solid oxide fuel cells (IT-SOFC). Amongst these compounds,...
A misbehavior‐tolerant multipath routing protocol for wireless Ad hoc networks [electronic resource]
, Article International Journal of Research in Wireless Systems (IJRWS) ; Vol. 2, Issue 9, pp. , Sep. 2013 ; Pakravan, Mohammad Reza ; Aref, Mohammad Reza ; Sharif University of Technology
Abstract
Secure routing is a major key to service maintenance in ad hoc networks. Ad hoc nature exposes the network to several types of node misbehavior or attacks. As a result of the resource limitations in such networks nodes may have a tendency to behave selfishly. Selfish behavior can have drastic impacts on network performance. We have proposed a Misbehavior-Tolerant Multipath Routing protocol (MTMR) which detects and punishes all types of misbehavior such as selfish behavior, wormhole, sinkhole and grey-hole attacks. The protocol utilizes a proactive approach to enforce cooperation. In addition, it uses a novel data redirection method to mitigate the impact of node misbehavior on network...
Power System Load Frequency Control Considering Renewable Energy Sources
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Power system frequency regulation entitled load frequency control (LFC) has been one of the important control problems in electric power system design and operation. Off-normal frequency can directly impact on power system operation and system reliability. A large frequency deviation can damage equipment, degrade load performance, cause the transmission lines to be overloaded and can interfere with system protection schemes, ultimately leading to an unstable condition for the power system . On the other hand, the increasing need for electrical energy in the 21st century, as well as limited fossil fuel reserves and the increasing concerns with environmental issues for the reduction of carbon...
Power System Frequency Control Enhancement Considering Wind Power Plants Participation
, Ph.D. Dissertation Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Synthetic inertial frequency response has attracted increasing attention due to the paradigm shift in power generation from synchronous generators toward wind turbines. Due to application of back-to-back converters in the structure of variable speed wind turbines (VSWTs), their shaft speeds become decoupled from the system frequency and thus, they cannot provide intrinsic inertial response. However, this type of response can be emulated via an extra auxiliary frequency controller or by modifying the conventional control system of the VSWTs. To achieve this goal, a frequency model of VSWT is developed in this dissertation. The power system's load-generation mismatch model is integrated into...
Intelligent-Based Anti-Islanding Methods in Distributed Generation
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Islanding detection methods are divided into three main groups as remote, active and passive. Although passive schemes have larger Non Detection Zones (NDZ) relative to other schemes, they are more used in utilities due to their low costs and less PQ problems than in other schemes. Passive Schemes are based on the measurements of passive system parameters. These parameters are measured at the point of common coupling (PCC). A new approach in passive techniques is the use of data-mining to classify the system parameters which affect the islanding detection. Therefore, by finding an efficient and robust data-mining algorithm, the inherent problem of passive schemes, which is their relatively...
Damping Controller Design for Inter-area Oscillations Using Wide-area Measurements
, Ph.D. Dissertation Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
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...
Modeling and Control of Magnetically-Levitated Iron-Less Planar Actuators
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Flying has fascinated mankind for ages. Nowadays, planar actuators are performing the same task as that, once a dream, of a flying magic carpet found in Persian mythology. Magnetically levitated planar actuators (MLPAs) consist of two parts; a moving part, and a stationary part. In most applications the moving part which is an array of permanent magnets (PMs) produces a magnetic flux density in the air-gap, and the stationary part, an array of current carrying coils, produces force and torque when it is exposed to the magnetic flux of the PM array. These actuators have been utilized in industry in applications where precise positioning is important. In recent years however, they have found...
Estimation of Wind turbine’s Produced Energy in Different Regions
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
One of the most important problems in using wind energy is the estimation of wind energy potential of a region with acceptable accuracy. To use wind energy and convert it to electrical energy it is necessary to study the economical aspects of wind farm installation, and to choose an appropriate wind turbine to be installed in a region. To do such a study and to choose approperiate wind turbine, annual energy output of different wind turbines should be estimated in that region. The porpuse of this thesis is to develop new methods to estimate annual energy production of a wind turbine by using some of the parameters of wind speed pattern of a region such as wind speed average, wind speed...
Frequency Control During Power System Restoration
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
The problem of restoring power systems after a complete or partial blackout is as old as the power industry itself. In recent years, due to economic competition and deregulation, power systems are operated closer and closer to their limits. At the same time, power systems have increased in size and complexity. Both factors increase the risk of major power outages. After a blackout, power needs to be restored as quickly and reliably as possible, and consequently, detailed restoration plants are necessary. This thesis concentrates on the initial stages of restoration where load pickup and frequency control problem is identified. The best sequence of load pickup for power plants during power...
Coordinated Power System Load Frequency Control via MPC
, Ph.D. Dissertation Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Load frequency control (LFC) is one of the important control problems in interconnected power system design and operation, and is becoming more significant today because of the increasing size, changing structure, emerging new uncertainties, environmental constraints and the omplexity of power systems. Therefore, load frequency function requires increased performance and flexibility to ensure that it is capable of maintaining a generation-load balance, following serious disturbances.Real power systems are often large-scale systems which are composed of many interacting subsystems. Therefore, it is difficult to control such systems due to the required inherent computational complexities and...
Optimization of Sizing and Operation for a Multi-Carrier Energy System
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Increasing energy demand and at the same time, considering exhaustible fossil fuel resources has led to increase distributed generation for reducing energy loss and increasing efficiency of energy systems specially due to technical development on generation systems that meet environmental and energy policy concerns. One of the most important distributed energy technologies is Combined Heat and Power (CHP). CHP is small, high efficiency, low installation time and self-contained electric generation plant that can provide power for household applications, commercial or industrial facilities and hence its applications are overtly increasing. It can reduce power loss and enhance service...
Optimization of Size and Operation of Energy Hub Considering Uncertainty
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Nowadays the growing demand for energy, and, on the other hand, the limited resources of fossil consuming energy in the world have caused the energy operation and consumption management to be taken into consideration much more than the past. Based on this background, improving the efficiency of feed conversion technologies in supplying the energy demanded by the consumers is the foremost and the most crucial solution to preventing energy loss. Another approach to reducing the losses through energy generation and transmission is the use of distributed energy generation systems in small scale. The advantages of applying this type of technology are the possibility of installing near the load...
Optimizing Smart Energy Hub Operation by Reinforcement Learning Approach
, M.Sc. Thesis Sharif University of Technology ; Ranjbar, Ali Mohammad (Supervisor)
Abstract
Nowadays, demands increment is one of the greatest concerns of energy systems operators. Consequently, enhancing the efficiency of consumption is an inevitable goal, which leads us to a concept named as energy hub (EH). In a simple definition, an EH is a multi-generation system where different energy carriers are converted and stored by various devices such as combined cooling, heating and power (CCHP), battery, and boiler to meet the load demands. In addition, with advent of smart grids (SG), demand side management (DSM) becomes one of the effective techniques with significant role in optimizing energy systems performance. DSM commonly refers to methods implemented by utility companies to...