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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...
Evaluation of spatial and temporal variation in water quality by pattern recognition techniques: A case study on Jajrood River (Tehran, Iran)
, Article Journal of Environmental Management ; Volume 91, Issue 4 , 2010 , Pages 852-860 ; 03014797 (ISSN) ; Abrishamchi, A ; Torkian, A ; Sharif University of Technology
2010
Abstract
In this paper, principal component analysis (PCA) and hierarchical cluster analysis (CA) methods have been used to investigate the water quality of Jajrood River (Iran) and to assess and discriminate the relative magnitude of anthropogenic and "natural" influences on the quality of river water. T, EC, pH, TDS, NH4, NO3, NO2, Turb., T.Hard., Ca, Mg, Na, K, Cl, SO4, SiO2 as physicochemical and TC, FC as biochemical variables have been analyzed in the water samples collected every month over a three-year period from 18 sampling stations along a 50 km section of Jajrood River that is under the influence of anthropogenic and natural changes. Exploratory analysis of experimental data has been...
Analytical model for the extraction of flaw-induced current interactions for SQUID NDE
, Article IEEE Transactions on Applied Superconductivity ; Volume 21, Issue 4 , 2011 , Pages 3442-3446 ; 10518223 (ISSN) ; Hosseini, M ; Razmkhah, S ; Mehrany, K ; Kokabi, H ; Schubert, J ; Banzet, M ; Krause, H. J ; Fardmanesh, M ; Sharif University of Technology
2011
Abstract
Incorporating an analytical approach to simulate the interaction of a series of long cracks and the induced current of a double-D excitation coil, we have developed a model-based method to do precise detection of the positions of the cracks in a metallic structure by using eddy-current superconducting quantum interference device (SQUID) nondestructive evaluation (NDE) measurements. Conventionally, the structure of the defects is found by iteratively solving a numerical forward problem, which is usually based on finite-element, boundary-element, or volume-integral method. This, however, incurs a heavy numerical burden, as every time the forward problem is to be solved, a rigorous numerical...
A Micro-FT-UART for safety-critical SoC-based applications
, Article International Conference on Availability, Reliability and Security, ARES 2009, Fukuoka, Fukuoka Prefecture, 16 March 2009 through 19 March 2009 ; 2009 , Pages 316-321 ; 9780769535647 (ISBN) ; Miremadi, S. G ; Ejlali, A. I ; Sharif University of Technology
2009
Abstract
This paper presents the design of a fault-tolerant universal asynchronous receiver transmitter (UART) called micro-FT-UART for safety-critical SoC-based applications. This UART exploits advantages of three fault-tolerant techniques to tolerate soft errors. The three techniques are triple modular redundancy (TMR), Hamming code and a new technique called correction by parity storing (CPS). An VHDL model of a micro-UART is simulated by the ModelSim v.6.0 and synthesized by the Synopsys Design Compiler v.X-2005.09- SP2. About 1000 single-bit errors and 1000 multiple-bit errors are injected into different parts of the micro-UART to find out the error sensitivity of each specific part. Considering...
A novel SET/SEU hardened parallel I/O port
, Article 2009 IEEE Circuits and Systems International Conference on Testing and Diagnosis, ICTD'09, Chengdu, 28 April 2009 through 29 April 2009 ; 2009 ; 9781424425877 (ISBN) ; Miremadi, S. G ; Ejlali, A ; Fazeli, M ; Sharif University of Technology
2009
Abstract
The continuous decrease in CMOS technology feature size increases the susceptibility of such circuits to single event transient SET and single event upset SEU, caused by energetic particles striking system wires and flip flops. This paper presents a novel SET/SEU-detection technique for I/O ports where different sampling times used to detect the effects of SET/SEUs. The power dissipation, area, reliability, and propagation delay of the SET/SEU-detection I/O port are analyzed by HSPICE v.X-2005.v9 simulation. The results show that this I/O port can detect all SET/SEUs, by consumption of about 113% more power and occupation of 145% more area than simple I/O port. ©2009 IEEE
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
Numerical Investigation of the Thermo-mechanical Response of Single Energy Pile and a Group of Energy Piles
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor) ; Ghasemi Fare, Omid (Co-Advisor)
Abstract
Geothermal piles are being used to serve dual purposes: transfer the structural load to the ground and act as heat exchanger elements to harvest and reject heat from and to the ground. Thermal loading can change the mechanical performance and bearing capacity of the geothermal piles during heating and cooling cycles. Therefore the thermo-mechanical responses of the geothermal piles should be comprehensively studied. In this paper the thermo-mechanical performance of a geothermal pile was analyzed using a 3D finite difference model in FLAC. The energy pile tests performed at Lambeth College, London were simulated using the developed numerical model. Comparison of both thermal strain and...
Response analysis of free-membrane transition-edge detectors with thin substrates
, Article Journal of Physics: Conference Series ; Volume 153 , 2009 ; 17426588 (ISSN) ; Khoshaman, A ; Razmkhah, S ; Hoseini, S. M ; Moftakharzadeh, A ; Bozbey, A ; Fardmanesh, M ; Sharif University of Technology
2009
Abstract
In this work, we have investigated and presented the bolometric response of freestanding membrane type of superconductive transition-edge detectors at micro-scale and submicron-scale substrate thicknesses. The technique applied here is based on the finite-size scaling method which is now extensively used for the calculation of thermal parameters of materials at low dimensions when the significance of surface energy contribution is not negligible compared to that of the total bulk energy. This method is used to evaluate the variation of specific heat per unit volume and heat conductivity and hence its effect on the total heat capacitance and conductance of the substrate versus its thickness....
Nonlinear interstory drift contours for idealized forward directivity pulses using "modified fish-bone" models
, Article Advances in Structural Engineering ; Volume 18, Issue 5 , May , 2015 , Pages 603-627 ; 13694332 (ISSN) ; Khosravi, H ; Jamnani, H. H ; Sharif University of Technology
Multi-Science Publishing Co. Ltd
2015
Abstract
Four 5-, 10-, 20- and 30-story moment frames, representing low-, mid-, and two high-rise structures, were subjected to a great number of idealized directivity pulses. The amplitudes and periods of pulses vary from 0.02 g to 1.0 g and 0.5 to 12 sec, respectively. Over 1400 nonlinear dynamic analyses of low- to high-rise moment frames were performed which were feasible through using modified fish-bone model. The distribution of interstory drift along the height was studied and two applied contours were proposed: (i) the maximum interstory drift contour, and (ii) the critical story contour. These contours were demonstrated versus the ratio of natural period of the structure to the pulse period...
Analysis of singularities of a 3DOF parallel manipulator based on a novel geometrical method
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Sadeghian, H ; Roozbehani, H ; Zohoor, H ; Sharif University of Technology
2006
Abstract
In this article singular points of a parallel manipulator are obtained based on a novel geometrical method. Here we introduce the constrained plain method (CPM) and some of its application in parallel mechanism. Given the definition of constraint plane (CP) and infinite constraint plane (ICP) the dependency conditions of constraints is achieved with the use of a new theorem based on the Ceva geometrical theorem. The direction of angular velocity of a body is achieved by having three ICPs with the use of another theorem. Finally, with the use of the above two novel theorems singularities of the 3UPF_PU mechanism are obtained. It should be emphasized that this method is completely geometrical,...
Melting enthalpy and entropy of freestanding metallic nanoparticles based on cohesive energy and average coordination number
, Article Journal of Physical Chemistry C ; Volume 115, Issue 35 , August , 2011 , Pages 17310-17313 ; 19327447 (ISSN) ; Delavari H., H ; Madaah Hosseini, H. R ; Sharif University of Technology
2011
Abstract
An analytical model is proposed to study the effect of particle size on melting enthalpy and entropy of metallic nanoparticles (NPs). The Mott's and Regel's equations for melting entropy in the combination of core average coordination number (CAC) and surface average coordination number (SAC) of freestanding NPs are considered. Clusters of icosahedral (IC), body centered cubic (BCC), and body centered tetragonal (BCT) structure without any vacancies and defects are modeled. Using the variable coordination number made this model to be in good agreement with experimental and molecular dynamic (MD) results of different crystal structures. The model predicts melting entropy and enthalpy of...
On the temperature and residual stress field during grinding
, Article WCE 2010 - World Congress on Engineering 2010, 30 June 2010 through 2 July 2010 ; Volume 2 , 2010 , Pages 1196-1200 ; 9789881821072 (ISBN) ; Farrahi, G. H ; Ghadbeigi, H ; Sharif University of Technology
2010
Abstract
Grinding is widely used for manufacturing of components that require fine surface finish and good dimensional accuracy. In this study a thermo-mechanical finite element analysis is conducted to find out how grinding parameters can affect temperature and residual stress distribution in the workpiece. Results of parametric study presented in this work indicate, by carefully selecting the grinding parameters, minimum thermal and mechanical damage can be achieved. Higher workpiece velocities produce higher surface residual stress. By increasing depths of cut, depth of tensile residual stresses increases. Convection heat coefficient does not have any considerable effect on surface residual stress...
A new lattic LP-based post filter for adaptive noise cancellers in mobile and vehicular applications
, Article Proceedings of the 8th IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2008, 16 December 2008 through 19 December 2008, Sarajevo ; 2008 , Pages 407-412 ; 9781424435555 (ISBN) ; Sameti, H ; Veisi, H ; Abutalebi, H. R ; Sharif University of Technology
2008
Abstract
Adaptive Noise Cancellation (ANC) is a well-known technique for background noise reduction in automobile and vehicular environments. The noise fields in automobile and other vehicle interior obey the diffuse noise field model closely. On the other hand, the ANC does not provide sufficient noise reduction in the diffuse noise fields. In this paper, a new multistage post-filter is designed for ANC as a solution to diffuse noise conditions. The designed post-filter is a single channel Linear Prediction (LP) based speech enhancement system. The LP is performed by an adaptive lattice filter and attempts to extract speech components by using intermediate ANC signals. The post-filter has no...
Finite element analysis of shot-peening effect on fretting fatigue parameters
, Article Tribology International ; Volume 44, Issue 11 , 2011 , Pages 1583-1588 ; 0301679X (ISSN) ; Alvandi Tabrizi, Y ; Farrahi, G. H ; Majzoobi, G. H ; Ghadbeigi, H ; Sharif University of Technology
2011
Abstract
Shot peening is widely used to improve the fretting fatigue strength of critical surfaces. Fretting fatigue occurs in contacting parts that are subjected to fluctuating loads and sliding movements at the same time. This paper presents a sequential finite element simulation to investigate the shot peening effects on normal stress, shear stress, bulk stress and slip amplitude, which are considered to be the controlling parameters of fretting damage. The results demonstrated that among the modifications related to shot peening, compressive residual stress has a dominant effect on the fretting parameters
Mechanically activated synthesis of single crystalline MgO nanostructures
, Article Journal of Alloys and Compounds ; Volume 506, Issue 2 , September , 2010 , Pages 715-720 ; 09258388 (ISSN) ; Yoozbashizadeh, H ; Askari, M ; Kobatake, H ; Fukuyama, H ; Sharif University of Technology
2010
Abstract
One-dimensional (1D) MgO structures were successfully synthesized via carbothermic reduction of mechanically activated mixture of MgO and graphite. Mechanical activation of source materials before carbothermic reduction can substantially enhance the formation of MgO products at a temperature (1000 °C) relatively lower than that required in previous approaches (≥1200 °C). However, the morphology of MgO formed is dependent on the degree of mechanical activation and the condition of the subsequent carbothermic reduction. Two distinctive morphologies were found for MgO products synthesized using our method: single crystalline nanorods with rectangular cross-sections whose diameters range from 50...
Boundary control design for vibration suppression and attitude control of flexible satellites with multi-section appendages
, Article Acta Astronautica ; Volume 173 , 2020 , Pages 22-30 ; Salarieh, H ; Nejat Pishkenari, H ; Jalili, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Attitude and vibration control of a general form of flexible satellites is addressed in this paper. Partial differential dynamic equations are derived considering new details such as multi sectioned solar panels and elastic connections between main hub and solar panels. Boundary control approach is adopted to eliminate simplification errors of discrete models, using just one actuator in the hub. Asymptotic stability of attitude dynamics is proved for a group of boundary controllers and necessary conditions for asymptotic stability of vibrations are discussed. Being independent of modeling accuracy and using easily measurable feedbacks are among advantages of the proposed class of...
Characterization and calcination behavior of a low-grade manganese ore
, Article Materials Today Communications ; Volume 25 , 2020 ; Becker, H ; Eftekhari, H ; Yoozbashizadeh, H ; Safarian, J ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Characterization and calcination behavior of a low-grade manganese ore, as a part of Mn ferroalloys production, was studied by XRF, ex-situ XRD, in-situ XRD, and SEM-EDS techniques. Calcination experiments were carried out at and up to 900 °C (1173 K) in air and argon atmospheres. The samples were in particles and powder forms. The results indicated that both quartz and calcite phases in the ore exhibit a bimodal spatial distribution; as relatively large regions and finely distributed in the Mn- and Fe-containing phases. By Rietveld analysis of the in-situ XRD data, the reactions occurring upon heating during the calcination process were deduced. Thermal decomposition and reactive diffusion...
Minimizing the error of time difference of arrival method in mobile networks
, Article 2005 International Conference on Wirelessand Optical Communications Networks, Dubai, 6 March 2005 through 8 March 2005 ; 2005 , Pages 328-332 ; 0780390199 (ISBN); 9780780390195 (ISBN) ; Aghababa, H ; Radfar, M. H ; Khalaj, B. H ; Sharif University of Technology
2005
Abstract
Estimating the position of a mobile set is of great importance in new mobile services. However, in most cases, the accuracy should be less than 100 meters. This accuracy is hard to reach especially in urban areas. The main problem is that there are a lot of obstacles like buildings between the BTS and the mobile set. Thus the time measured between BTS and the mobile set is somehow greater than the time it takes the wave to travel directly between two points. This paper introduces an optimized solution for TDOA as one of the most efficient ways for finding the location of a mobile phone. Considering the standards and limitations of both GSM and UMTS, the Authors present a solution for...
A fast and novel method of pattern synthesis for non-uniform phased array antennas
, Article Proceedings International Radar Symposium, 24 June 2015 through 26 June 2015 ; Volume 2015-August , 2015 , Pages 924-929 ; 21555753 (ISSN) ; 9783954048533 (ISBN); 9783954048533 (ISBN); 9783954048533 (ISBN) ; Sebt, M. A ; Nayebi, M. M ; Behroozi, H ; Rohling, H ; Rohling, H ; Rohling, H ; Sharif University of Technology
IEEE Computer Society
2015
Abstract
Weighting elements to achieve radiation patterns with desired characteristics is a classical work in phased array antennas. These characteristics can be low sidelobe level, narrow beamwidth, high directivity, pattern nulling in special angle and etc. For each of these characteristics, different methods have been introduced. Most of methods have been presented for uniform arrays, however there are lots of methods to obtain a desired pattern for antennas with non-uniform element distances. The problem with these methods is complexity or not very good results. In this paper, fast and easy methods based on Least Square Error that leads to good results are presented. In addition, weighting of...
Size-dependent interaction of an edge dislocation with an elliptical nano-inhomogeneity incorporating interface effects
, Article International Journal of Solids and Structures ; Volume 49, Issue 5 , March , 2012 , Pages 759-770 ; 00207683 (ISSN) ; Ahmadzadeh Bakhshayesh, H ; Gutkin, M. Y
2012
Abstract
The elastic behavior of an edge dislocation, which is positioned outside of a nanoscale elliptical inhomogeneity, is studied within the interface elasticity approach incorporating the elastic moduli and surface tension of the interface. The complex potential function method is used. The dislocation stress field and the image force acting on the dislocation are found and analyzed in detail. The difference between the solutions obtained within the classical-elasticity and interface-elasticity approaches is discussed. It is shown that for the stress field, this difference can be significant in those points of the inhomogeneity-matrix interface, where the radius of curvature is smaller and which...