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magnetic-shielding
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Fundamental mode fluxgate magnetometers for active magnetic shielding
, Article 2011 19th Iranian Conference on Electrical Engineering, ICEE 2011, 17 May 2011 through 19 May 2011 ; May , 2011 , Page(s): 1 ; ISSN : 21647054 ; 9789644634284 (ISBN) ; Eshraghi, M. J ; Forooghi, F ; Sarreshtedari, F ; Fardmanesh, M ; Sharif University of Technology
2011
Abstract
Fluxgate magnetometers with different design and core materials have been made. The sensors have been characterized and the frequency responses of the sensors have been measured. The fluxgate magnetometer based on orthogonal design and amorphous wire core working in fundamental mode reaches 30pT/Hz noise level and 40μV/nT sensitivity. Finally an active magnetic shield constructed based on the amorphous core fluxgate magnetometer reaches more than 60dB field attenuation for DC field and has a good response for frequencies below 100Hz
Excitation current optimization of fluxgate magnetometers for active magnetic shielding of SQUID-based magnetocardiography system
, Article Journal of Superconductivity and Novel Magnetism ; Volume 30, Issue 8 , 2017 , Pages 2323-2328 ; 15571939 (ISSN) ; Kalantari, N ; Jabbari, T ; Fardmanesh, M ; Sharif University of Technology
Abstract
In order to achieve stable operation for a developed high-Tc SQUID-based magnetocardiography system, a two-stage active magnetic shielding technique is implemented. This technique is based on a combination of fluxgate and high-Tc SQUID magnetometers feedback loops. While two YBCO rf SQUIDs in a gradiometric configuration are used at liquid Nitrogen temperature as the main sensors for the heart signal detection and low-amplitude noise signals cancellation in one stage, a fluxgate is used to cancel large far-field environmental noise in the other stage feedback loop. The fluxgate sensors working in the fundamental mode under the optimized bias conditions have white noise levels less than 10...
Prediction of gas-phase 13C nuclear magnetic shielding constants using ONIOM and optimally selected basis functions
, Article Concepts in Magnetic Resonance Part A: Bridging Education and Research ; Volume 32, Issue 6 , 2008 , Pages 449-461 ; 15466086 (ISSN) ; Shaghaghi, H ; Jalali Heravi, M ; Sharif University of Technology
2008
Abstract
The wave functions for calculating gas-phase 13C nuclear magnetic shielding constants of 22 molecules have been optimally selected using factorial design as a multivariate technique. GIAO and CSGT methods were used for computation of shielding constants. Different wave functions for different types of carbons were recommended. A wave function as the best level of the theory is proposed for almost similar carbons. ONIOM approach for molecules with different types of carbons is applied. The results of GIAO method using the proposed wave function are in very good agreement with the experimental values. An additional series (21 carbons) were used as test sets and their results confirmed the...
Excitation current optimization of fluxgate magnetometers for active magnetic shielding of SQUID-Based magnetocardiography system
, Article Journal of Superconductivity and Novel Magnetism ; 2016 , Pages 1-6 ; 15571939 (ISSN) ; Kalantari, N ; Jabbari, T ; Fardmanesh, M ; Sharif University of Technology
Springer New York LLC
Abstract
In order to achieve stable operation for a developed high-Tc SQUID-based magnetocardiography system, a two-stage active magnetic shielding technique is implemented. This technique is based on a combination of fluxgate and high-Tc SQUID magnetometers feedback loops. While two YBCO rf SQUIDs in a gradiometric configuration are used at liquid Nitrogen temperature as the main sensors for the heart signal detection and low-amplitude noise signals cancellation in one stage, a fluxgate is used to cancel large far-field environmental noise in the other stage feedback loop. The fluxgate sensors working in the fundamental mode under the optimized bias conditions have white noise levels less than 10...
Design & Implementation of Fluxgate Based Active Shield for Using in SQUID Based Magnetocardiograghy
, M.Sc. Thesis Sharif University of Technology ; Fardmanesh, Mehdi (Supervisor)
Abstract
Superconducting Quantum Interference Devices (SQUIDs) are one of the most sensitive magnetic flux detectors. According to their high sensitivity, these sensors have many applications such as magnetic imaging, magnetocardiography and magnetoencephalography. In this project we have designed and implemented a fluxgate based active shield that would be used in magnetocardiography. One of the main concerns in RF-SQUID applications is suppression of the low and high frequency noises. These noise sources includes earth magnetic force, humming noise and RF noise caused by cell phones. These sources could unlock RF-SQUID sensors and hence needs to be shielded. Low frequency noise suppression could be...
Design and Fabrication of Inductive High Temperature Superconducting Fault Current Limiter
,
Ph.D. Dissertation
Sharif University of Technology
;
Vakilian, Mehdi
(Supervisor)
;
Fardmanesh, Mehdi
(Supervisor)
Abstract
The continuous rise in electricity demand and the ever growing power generation in different power networks over the world have caused the short circuit level in the power systems to exceed the operational rating of the installed power devices (including cables, circuit breakers and buses). Replacing these devices with new higher rating devices is an expensive solution. From this point of view, utilizing fault current limiters is an economical solution. Superconducting fault current limiters form an efficient category of current limiters. This type is expected to be studied and used widely in future due to their advantages. In this thesis, the first chapter reviews the superconductivity...
Design and Fabrication of Sensor Probe and Active Noise Reduction Circuit for SQUID MCG System in Magnetically Unshielded Environment
,
M.Sc. Thesis
Sharif University of Technology
;
Fardmanesh, Mehdi
(Supervisor)
Abstract
Characterization of local magnetic activity of the heart muscles is named magnetocardiography (MCG), which measures magnetic field generated by electrical activity around heart. RF SQUID sensors are appropriate choice for measuring magnetic activity of the heart muscles. Because squid detects weak signals as low as fTesla, while heart magnetic field is near 50 pt which is one millionth of earth magnetic field and thousands of time weaker than the environment noise. One of the problems of mcg system is its urgency to shielding of unwanted magnetic field. In this project design of holders and resonators for well coupled input coil with RF SQUID is improved. As a result, at the first stage...
Signal enhancement techniques for rf SQUID based magnetic imaging systems
, Article Superconductor Science and Technology ; Volume 19, Issue 8 , 2006 , Pages 821-824 ; 09532048 (ISSN) ; Fardmanesh, M ; Schubert, J ; Zander, W ; Banzet, M ; Lomparski, D ; Schmidt, M ; Krause, H. J ; Sharif University of Technology
2006
Abstract
We have investigated the rf SQUID (radio-frequency superconducting quantum interference device) and its coupling to tank circuit configurations to achieve an optimal front-end assembly for sensitive and high spatial resolution magnetic imaging systems. The investigation of the YBCO rf SQUID coupling to the conventional LC tank circuits revealed that coupling from the back of the SQUID substrate enhances the SQUID signal while facilitating the front-end assembly configuration. The optimal thickness of the substrate material between the SQUID and the tank circuit is 0.4 mm for LaAlO3 resulting in an increase of the SQUID flux-voltage transfer function signal, Vspp, of 1.5 times, and 0.5 mm for...
Design and Optimization of HTS SQUID based Magnetocardiography using Active Shield
, Ph.D. Dissertation Sharif University of Technology ; Fardmanesh, Mehdi (Supervisor)
Abstract
In this work, we report on a developed single-channel high-Tc SQUID based MCG system for operation in unshielded environment. In brief, our system consists of a liquid Nitrogen Dewar and two high-Tc rf-SQUID capsuled in a holding probe,which is connected via coaxial cables to our multichannel rf-SQUID readout electronics.The rf-SQUIDs were patterned from about 200 nm△10 nm thick YBCO films sputtered on 1 mm thick LaAlO3 substrates. The holding probe integrates rf-SQUIDs, LC resonant circuits, and shielding coils. We have investigated the effects of the lumped element tank circuit resonator parameters on the rf-SQUID signal characteristics and based on the simulation and experimental...
Electromagnetic interference shielding effectiveness of Al/SiC composite foams
, Article Journal of Materials Science: Materials in Electronics ; Volume 26, Issue 10 , 2015 , Pages 7530-7536 ; 09574522 (ISSN) ; Lalegani, Z ; Sharif University of Technology
Springer New York LLC
2015
Abstract
Closed cell aluminum foams are fabricated by using the casting method. The electromagnetic interference (EMI) shielding effectiveness of foams are investigated in the frequency range of 1.44–5 and 8–12 GHz (X band).The shielding materials are made of Al foam with the addition of different concentrations of SiC (5, 10, 15 wt%). Results show that the Al/SiC composite foams have good shielding effectiveness. EMI shielding effectiveness of samples generally increased with increasing porosity and with the increasing of SiC content. The sample with 15 wt% SiC had shielding effectiveness values of up to 150 dB
Shielding factor enhancement method for Bi-stage active shield in SQUID-based magnetocardiography system
, Article 29th Iranian Conference on Electrical Engineering, ICEE 2021, 18 May 2021 through 20 May 2021 ; 2021 , Pages 129-133 ; 9781665433655 (ISBN) ; Esmaeili, F ; Shanehsazzadeh, F ; Fardmanesh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
We proposed a simple method to enhance shielding factor of our previously proposed bi-stage active shield system employed in a SQUID-based magnetocardiography system. The additional proposed design is optimized for canceling the power-line magnetic interference field to provide a calmer magnetic environment for the bi-stage active shield. A 50 Hz cancellation coil is placed around the bi-stage shielding system which includes inner and outer coils designed for compensating low-frequency (0-0.1Hz) and high-frequency (0.1-100Hz) environmental magnetic noise, respectively. In this configuration, a SQUID magnetometer is located at the center of these coils. Considering that the power-line...
Shielding factor enhancement method for bi-stage active shield in SQUID-based magnetocardiography system
, Article 29th Iranian Conference on Electrical Engineering, ICEE 2021, 18 May 2021 through 20 May 2021 ; 2021 , Pages 129-133 ; 9781665433655 (ISBN) ; Esmaeili, F ; Shanehsazzadeh, F ; Fardmanesh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
We proposed a simple method to enhance shielding factor of our previously proposed bi-stage active shield system employed in a SQUID-based magnetocardiography system. The additional proposed design is optimized for canceling the power-line magnetic interference field to provide a calmer magnetic environment for the bi-stage active shield. A 50 Hz cancellation coil is placed around the bi-stage shielding system which includes inner and outer coils designed for compensating low-frequency (0-0.1Hz) and high-frequency (0.1-100Hz) environmental magnetic noise, respectively. In this configuration, a SQUID magnetometer is located at the center of these coils. Considering that the power-line...
Environmental noise cancellation for high-TC SQUID-based magnetocardiography systems using a bistage active shield
, Article IEEE Transactions on Applied Superconductivity ; 2017 ; 10518223 (ISSN) ; Kalantari, N ; Sarreshtedari, F ; Fardmanesh, M ; Sharif University of Technology
Abstract
An active noise cancellation method is proposed for superconducting quantum interference devices (SQUID)-based magnetocardiography systems working out of magnetically shielded rooms. Using YBCO high-Tc rf-SQUID magnetometers as magnetic field sensors, an active shielding system was implemented based on this method. This method incorporates two different shielding frequency regimes of operation simultaneously. This is because the unwanted background magnetic field signals range from very low frequencies up to high frequencies with a wide range of amplitudes at the upper and lower frequency spectra. Therefore, the shielding system is designed in a bistage configuration, and each stage covers...
Low noise active shield for SQUID-Based mag-netocardiography systems
, Article IEEE Transactions on Applied Superconductivity ; 2017 ; 10518223 (ISSN) ; Fardmanesh, M ; Sharif University of Technology
Abstract
light weight and low-cost active magnetic shield sys-tem is proposed for a single channel SQUID-based magnetocardiog-raphy system equipped for operating at liquid nitrogen temperature without passive magnetic shield. The developed active shield, using coils around the sensors, is a two-stage magnetic shielding system, each stage of which has been designed to compensate different fre-quency and dynamic ranges. The sensor part contains two high-Tc rf-SQUID magnetometers, capable of working stably under earth magnetic field, placed in an axial gradiometric arrangement with a baseline of 10 cm. The active shield setup is driven using two corre-lated proportional-integral-derivative closed loop...
Low noise active shield for SQUID-based magnetocardiography systems
, Article IEEE Transactions on Applied Superconductivity ; Volume 28, Issue 4 , 2018 ; 10518223 (ISSN) ; Fardmanesh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
A light weight and low-cost active magnetic shield system is proposed for a single channel SQUID-based magnetocardiography system equipped for operating at liquid nitrogen temperature without passive magnetic shield. The developed active shield, using coils around the sensors, is a two-stage magnetic shielding system, each stage of which has been designed to compensate different frequency and dynamic ranges. The sensor part contains two high-Tc rf-SQUID magnetometers, capable of working stably under earth magnetic field, placed in an axial gradiometric arrangement with a baseline of 10 cm. The active shield setup is driven using two correlated proportional-integral-derivative closed loop...
Partly semiconductor covered vane fast magnetron
, Article IEEE Transactions on Plasma Science ; Volume 50, Issue 5 , 2022 , Pages 1179-1187 ; 00933813 (ISSN) ; Hashemi, S. M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Alterations in the structure of a magnetron, e.g., the A6 relativistic magnetron, are proposed, which considerably increase the device's build-up speed. We cover the magnetron vane surfaces with semiconductor layers of nonzero electric conductivity, with an exact geometrical design. Semiconductor layers with considerable mechanical strength also provide excellent shielding for the vanes against the high-energy relativistic electrons' bombardment. The novel structure introduces several new free parameters to the magnetron design procedure and considerably increases the design flexibility. A multistage exact optimization procedure, performed by extensive computer simulations, shows that...