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A Structural Health Monitoring System for Storage Tanks by Using Fiber Optic Sensor
, M.Sc. Thesis Sharif University of Technology ; Zabihollah, Abolgassem (Supervisor)
Abstract
Storage tanks are always under different hazards such as corrosion and leaking. In this thesis after studding current damaged detection methods, a new method of corrosion monitoring on storage tanks was performed. Fiber optic technology was explained and Fiber Bragg grating (FBG) was chosen as a sensor. Modeling of optical fiber and storage tank was performed in ANSYS and corrosion damage, in the form of pitting, in two possible states of occurrence was presented. The effect of change of strain, thickness, loading, length, and wavelength on each other was presented in different graphs. The results showed that by decreasing thickness of elements, strain in the damaged area increased and by...
Performance Analysis and Optimization of Optically Steered Arrayed Antennas with Gratings
, Ph.D. Dissertation Sharif University of Technology ; Akbari, Mahmood (Supervisor)
Abstract
It is well known that arrays of antennas make it possible to steer the radiation pattern without steering a physical structure. For the past few decades this has been considered for many civil and military communication systems. Recently, ultra-short pulses are considered for high resolution radars and ultra-wideband communication systems. Systems with short pulses and large antenna arrays may benefit from high resolution in both temporal and spatial domains. But the implementation of the ultra-wideband feeding circuits for such antenna arrays is a hard job even with state of the art electronics. Optical technology has been applied, successfully, to a number of radio applications such as...
Analysis & Design of Bragg Mirror-Based Optical Fibers
, M.Sc. Thesis Sharif University of Technology ; Mehrany, Khashayar (Supervisor)
Abstract
The Bragg reflection mechanism is in this thesis employed to design optical fibers with specific characteristics. First, optical Bragg fibers (BF) with radial periodicity are considered and optimized to have the minimum leakage loss by introduction of a new parameter referred to as the point-wise wave-number. In this fashion, the optical effects of geometrical factors of the to-be-designed fiber are brought together in the point-wise wave-number and the sought-after parameters of the fiber are thus analytically found. Despite a few approximations made in extraction of optimum parameters, rigorous numerical analysis of the here-proposed optical BF clearly demonstrates that it outperforms...
Small Signal Analysis of Fiber Bragg Grating (FBG) Arrays and Experimental Verification
, Ph.D. Dissertation Sharif University of Technology ; Behnia, Fereidoon (Supervisor)
Abstract
In-fiber and all-optical wavelength-selective signal processing are key aspects of fiber Bragg grating (FBG)-based devices in optical communication systems. FBGs with sharp filtering properties have already been used in fiber optic communication networks as dispersion compensators, optical add–drop multiplexers, fiber lasers, and optical label switching modules. We have developed an in-fiber wavelength-selective optical intensity modulator to superimpose low rate overhead data on the transit high-speed payload signals. The tunable fiber Bragg grating (FBG), as the heart of a wavelength-selective modulator (WSM), is designed and properly biased to implement the desired modulation...
Condition Monitoring of Wind Turbine Blade Using Fiber Optics
, M.Sc. Thesis Sharif University of Technology ; Zabihollah, Abolghasem (Supervisor) ; Behzad, Mehdi (Co-Advisor)
Abstract
Over the last decades the attention of the most modern countries about usage of wind has grown due to the recent crisis of energy. This renewable energy source offers a cost effective solution for electricity production. Wind energy is the best candidate among other sources due to wind turbines technology reliability. In order to gain maximum power from wind turbines, their size becomes relatively large, which creates more complexity in their repair and maintenance, furthermore Wind turbine downtime is outside the expectations, which is more costly than corrective maintenance, therefore in order to minimize sudden downtimes and related huge maintenance, a reliable monitoring technique must...
Design and Development of Multi-Sensor Array for Structural Health Monitoring of Pipelines
, M.Sc. Thesis Sharif University of Technology ; Zabihollah, Abolghasem (Supervisor)
Abstract
Structural Health Monitoring (SHM) of pipelines is an important task for economic/safety reasons which depends on the method of study of the integrity profile of the pipeline structure. Process pipes, particularly, pipelines in thermal power plants are susceptible to stress corrosion cracking (SCC). Failure of these pipes may result in catastrophic damages, thus, require systematic regular inspections. The damage assessment may demand embedding of appropriate sensors and specific data analysis techniques. According to what is reported from the respective experiments, data analysis of a single sensor may not be adequate to provide a reasonable damage assessment, and in turn to making a...
In-fiber wavelength-selective modulation of WDM channels with performance analysis
, Article Journal of Lightwave Technology ; Volume 28, Issue 1 , 2010 , Pages 141-147 ; 07338724 (ISSN) ; Behnia, F ; Sharif University of Technology
Abstract
An in-fiber wavelength-selective optical intensity modulator has been developed to superimpose low-rate overhead (OH) data on the transit high-speed payload signals. The tunable fiber Bragg grating, as the heart of a wavelength-selective modulator (WSM), is designed and properly biased to implement the desired modulation specification. Potential performance limitations of WSM are investigated and described in terms of eye opening penalty and crosstalk between wavelength-division-multiplexing channels. A simple OH/label erasing technique is also provided and used for modifying the labels through cascaded WSMs. The performance of such cascaded systems is calculated both with and without...
Multi sensing grasper for minimally invasive surgery
, Article IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM, 3 July 2011 through 7 July 2011, Budapest ; July , 2011 , Pages 344-349 ; 9781457708381 (ISBN) ; Zabihollah, A ; Adldoost, H ; Sharif University of Technology
2011
Abstract
In the present work, a multi sensing grasper has been developed for minimally invasive surgery with embedded ZnO piezoelectric and Fiber Bragg Grating sensors. In this model, a sensing patch equipped with three FBG sensors to sense the temperature in rage of 800 n.m and two separated FBG in range of 1550 m.m to detect the displacement in x and y directions. ZnO piezoelectric is highly sensitive to time and provides a good resistance to temperature. Therefore, this sensor is used for measuring the rate of strain and creep coefficient. A finite element approach based on the viscous material theory and plane displacement theory of anisotropic materials has been utilized to obtain the compliance...
Photonic Methods for Ultra-broadband RF Arbitrary Waveform Generation
, Ph.D. Dissertation Sharif University of Technology ; Akbari, Mahmood (Supervisor) ; Mehrany, Khashayar (Co-Advisor)
Abstract
This thesis includes five major parts and eight chapters. In the first part, the literature of arbitrary waveform generation is reviewed. The expansion and diversity of telecommunication services like WIMAX , UWB , RoF , satellite telemetry methods and sensor networks require ultra-broadband arbitrary waveform generation methods. The ultra-broadband signals are those signals with normalized bandwidth (%BW is the ratio of signal’s bandwidth to the central frequency) over 15%. The main approach to enjoy the advantages of photonic processing is to modulate microwave signal with the light and then feed it to the optical signal processor. This light processor in case of linearity is called...
Vibration monitoring of wind turbine blade using fiber bragg grating
, Article Wind Engineering ; Volume 34, Issue 6 , 2010 , Pages 721-731 ; 0309524X (ISSN) ; Zabihollah, A ; Zareie, S ; Sharif University of Technology
2010
Abstract
Rapid growth in generating power from wind turbines led to application of long laminated composite blades. However, as the length of blades increases, the risk of failure due to excessive vibration increases. Therefore, a reliable wind power generator requires an efficient and accurate, yet economical structural health monitoring system to detect vibration and apply a reliable control to prevent from unpredicted failure. This paper presents an optimal, low cost and continuous vibration monitoring system for laminated composite blades using Fiber Bragg Grating (FBG). Utilizing a layerwise displacement theory, the Finite Element (FEM) model has been developed for the wind turbine blade. The...