Loading...
Search for:
magnetic-flux
0.011 seconds
Total 31 records
Analysis of a Ferromagnetic Segment using Magnetic Flux Leakage Method for Detecting Defect
, M.Sc. Thesis Sharif University of Technology ; Zohoor, Hassan (Supervisor)
Abstract
Magnetic flux leakage is one of the nondestructive testing methods used for ferromagnetic segments. The basis of performance of the magnetic flux leakage nondestructive testing is such that the ferromagnetic segment will be led to magnetic saturation by a powerful magnetic field, and if there was defect and decreasing in cross section, the segment's capability of transmitting magnetic flux will be decreased and therefore, some of passing magnetic flux from the under testing segment, will be leaked to the surrounding area. So the amount of magnetic flux leakage can be a criterion of existing defect in the segment. To estimate sizing of the defect, it's necessary to study the ingredients which...
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...
Modeling and parametric studies of magnetic shape memory alloy–based energy harvester
, Article Journal of Intelligent Material Systems and Structures ; Volume 29, Issue 4 , 2018 , Pages 563-573 ; 1045389X (ISSN) ; Rostami Najafabadi, H ; Askari Farsangi, M. A ; Sharif University of Technology
SAGE Publications Ltd
2018
Abstract
This article presents a model to simulate the behavior of a magnetic shape memory alloy while harvesting vibratory energy. In this type of energy harvester, magnetic shape memory alloy element is placed in the air gap of a ferromagnetic core which conducts the magnetic flux. Two apparent coils are wound around a ferromagnetic core: one to produce bias magnetic field by passing a rectified electric current and the other to serve as an energy pickup coil. Applying compressive time-variant strain field to magnetic shape memory alloy element changes its dimensions and magnetic properties as well. Presence of the bias magnetic field returns magnetic shape memory alloy element to its initial state...
The effect of a non-uniform pulse-width modulated magnetic field with different angles on the swinging ferrofluid droplet formation
, Article Journal of Industrial and Engineering Chemistry ; Volume 84 , 2020 , Pages 106-119 ; Favakeh, A ; Shafii, M. B ; Sharif University of Technology
Korean Society of Industrial Engineering Chemistry
2020
Abstract
In this study, ferrofluid droplet formation from a nozzle in the presence of a non-uniform Pulse-Width Modulated (PWM) magnetic field with different angles was studied experimentally. A Drop-on-Demand platform was introduced and three different regimes of droplet formation were observed. The regime map of the droplet formation was presented. A new type of droplet formation evolution was observed in which the droplet is formed while it is swinging around the nozzle, and the satellite droplet is not generated in this regime. The effects of five important parameters including magnetic flux density, applied magnetic frequency, duty cycle, distance between the nozzle and the center of the upper...
Approach for analytical modelling of axial-flux PM machines
, Article IET Electric Power Applications ; Volume 10, Issue 6 , 2016 , Pages 441-450 ; 17518660 (ISSN) ; Abedini Mohammadi, A ; Oraee, A ; Oraee, H ; Sharif University of Technology
Institution of Engineering and Technology
2016
Abstract
In the presented paper, an analytical model is developed for calculation of the air gap magnetic flux density in the axial-flux surface-mounted PM machines. The slotting effect is taken into account in the air gap magnetic flux distribution, accurately. The main novelty of this study is replacing the stator teeth by some surface currents at the border of the removed stator teeth. The uniqueness theorem is applied to find the surface currents. The two-dimensional (2D) field solution in the slotless machine is solved easily by separation of variables method. The multi-slice quasi-3D method is applied for taking 3D nature of field distribution into account. In addition, the back-EMF, armature...
A novel inertial energy harvester using magnetic shape memory alloy
, Article Smart Materials and Structures ; Volume 25, Issue 10 , 2016 ; 09641726 (ISSN) ; Sayyaadi, H ; Zakerzadeh, M. R ; Sharif University of Technology
Institute of Physics Publishing
2016
Abstract
This paper studies the output voltage from a novel inertial energy harvester using magnetic shape memory alloys (MSMAs). The MSMA elements are attached to the root of a cantilever beam by means of two steps. In order to get electrical voltage, two coils are wound around the MSMAs and a shock load is applied to a tip mass at the end of the beam to have vibration in it. The beam vibration causes strain in the MSMAs along their longitudinal directions and as a result the magnetic flux alters in the coils. The change of magnetic flux in the surrounding coil produces an AC voltage. In order to predict the output voltage, the nonlinear governing equations of beam motion based on Euler-Bernoulli...
Magnetic equivalent circuit model for wound rotor resolver without rotary transformer's core
, Article IEEE Sensors Journal ; Volume 18, Issue 21 , 2018 , Pages 8693-8700 ; 1530437X (ISSN) ; Alipour Sarabi, R ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Resolvers are widely used in the control of industrial inverter driven motors. Among different types of resolvers, disk-type wound-rotor resolvers have superior performance under mechanical faults. However, the rotary transformer's (RT's) presence in the inner side of the resolver's core leads to additional radial length. To overcome this problem, disk-type wound-rotor resolver without RT's core has been proposed. However, the optimization using time stepping finite-element method (TSFEM) is time consuming due to 3-D structure of this resolver. Accordingly, in this paper, an analytical model based on the magnetic equivalent circuit is proposed for the design and optimization process. The...
Computation of armature reaction field and full-load characteristics of an axial flux surface mounted pm machine using a new analytical approach
, Article 26th Iranian Conference on Electrical Engineering, ICEE 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 1027-1031 ; 9781538649169 (ISBN) ; Sharifi, A. H ; Abedini Mohammadi, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
In recent years axial flux permanent magnet (AFPM) machines have found industrial applications because of such characteristics as high power density, compact structure and disc-like shape. Like other electrical machines, prediction of flux density distribution in the air gap of AFPM is essential. In this paper, an analytical method for calculation of air gap flux density caused by armature reaction is presented. The solution is based on Maxwell's equations. Separation of variables method is applied to field equations and 2D distribution of magnetic flux density in the air gap calculated in term of Fourier series. The 2-D distribution of three-phase armature winding is modeled exactly....
Design-oriented modelling of axial-flux variable-reluctance resolver based on magnetic equivalent circuits and Schwarz-Christoffel mapping
, Article IEEE Transactions on Industrial Electronics ; Volume 65, Issue 5 , May , 2018 , Pages 4322-4330 ; 02780046 (ISSN) ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Axial flux variable reluctance (AFVR) resolvers have substantial benefits that make them suitable for motion control drives. However, they suffer from insufficient accuracy, especially in high-accuracy applications. Hence, optimizing the AFVR resolver structure is necessary for improving its commercial usage. However, its accurate modelling needs three-dimensional (3-D) time stepping finite element analysis (TSFEA) that is computationally expensive and unsuitable for co-usage with optimization algorithms. The aim of this paper is to establish an accurate, yet computationally fast, model suitable for optimal design of AFVR resolvers. The working of the proposed model is based on magnetic...
An electromagnetic design of slotless variable reluctance PM-Resolver
, Article IEEE Transactions on Industrial Electronics ; 2022 , Pages 1-10 ; 02780046 (ISSN) ; Tootoonchian, F ; Mahmoudi, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This paper proposes a novel design of the variable reluctance permanent magnet (VRPM) resolvers. It utilizes a slotless stator to reduce the resolver volume. The proposed design overcomes the complex structure of windings by replacing them with magnetic flux measurement units (MFMU). The new design eliminates the computationally-expensive demodulation process of output signals by relying on none-modulated signals. An analytical model based on the nonlinear magnetic equivalent circuit (MEC) method is used to extract the output signals of the proposed resolver design. The accuracy of applied analytical model is verified against the time-stepping finite-element method (TSFEM). An optimization...
Ferrofluid droplet manipulation using an adjustable alternating magnetic field
, Article Sensors and Actuators, A: Physical ; Volume 301 , 2020 ; Favakeh, A ; Sedighi, E ; Shafii, M. B ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Magnetically actuated droplet manipulation offers a promising tool for biomedical and engineering applications, such as drug delivery, biochemistry, sample handling in lab-on-chip devices and tissue engineering. In this study, characteristics of an adjustable alternating magnetic field generated by a magnetic coil for droplet manipulation was investigated which enables more control on droplet transport, and it can be considered as a suitable alternative for moving magnets or an array of micro-coils. By adjusting the magnetic flux density, the duty cycle and applied magnetic frequency, the manipulation of water-based ferrofluid droplets with a bio-compatible surfactant for different volumes...
Sensorless control of non-salient PMSM using simultaneous injection of two HF signals
, Article Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC ; March , 2014 , p. 2463-2468 ; Yaghoubi, M ; Tahami, F ; Bakhshai, A ; Jain, P. K ; Sharif University of Technology
Abstract
In recent years sensorless techniques based on HF carrier injection have become very popular as they are capable to estimate rotor position in a wide speed range. They can provide precise control over interior PMSMs without the accompanying need for a position sensor. However, in surface-mounted PMSMs, the estimation of rotor position is only reliable at light loads due to the very small saliency arising from main flux saturation. The anisotropy caused by stator flux saturation is not necessarily in alignment with rotor position especially at heavy loads. In this paper a novel solution is proposed to make use of the sensorless scheme in a surface-mounted PMSM even at heavy loads
Peculiar transport properties in Z-shaped graphene nanoribbons: A nanoscale NOR gate
, Article Thin Solid Films ; Volume 548 , 2013 , Pages 443-448 ; 00406090 (ISSN) ; Khoeini, F ; Shokri, A ; Sharif University of Technology
2013
Abstract
A nanoscale logic NOR gate has been theoretically designed by magnetic flux inputs in a Z-shaped graphene nanoribbon composed of an armchair ribbon device sandwiched between two semi-infinite metallic zigzag ribbon leads. The calculations are based on the tight-binding model and iterative Green's function method, in which the conductance as well as current-voltage characteristics of the nanosystem are calculated, numerically. We show that the current and conductance are highly sensitive to both the magnetic fluxes subject to the device and the size of the system. Our results may have important applications for building blocks in the nanoelectronic devices based on graphene nanoribbons
High-fidelity magnetic characterization and analytical model development for switched reluctance machines
, Article IEEE Transactions on Magnetics ; Volume 49, Issue 4 , 2013 , Pages 1505-1515 ; 00189464 (ISSN) ; Kaboli, S ; Davoudi, A ; Moayedi, S ; Sharif University of Technology
2013
Abstract
This paper proposes a new experimental procedure for magnetic characterization of switched reluctance machines. In the existing methods, phase voltage and current data are captured and further processed to find the flux linkage. Conventionally, assuming zero initial flux value, the flux linkage can be found by integrating the corresponding voltage term. However, the initial flux value is usually unknown, e.g., it can be nonzero when the current is zero due to the residual flux effect, and, thus, imposes error in magnetic characterization. The proposed method addresses this issue by considering an additional equation in steady state. This method injects a low-frequency sinusoidal current to...
Experimental study of a novel Magneto Mercury Reciprocating (MMR) micropump, fabrication and operation
, Article Sensors and Actuators, A: Physical ; Volume 194 , 2013 , Pages 277-284 ; 09244247 (ISSN) ; Salari, A ; Shafii, M. B ; Sharif University of Technology
2013
Abstract
Today, MEMS have wide applications in modern technologies. Magneto hydro dynamic (MHD) micropumps play an important role in the MEMS industry and have been thoroughly studied in the recent years. In this study, the idea of classic reciprocating micropumps was combined with magneto hydro dynamics (MHD) to develop a novel Magneto Mercury Reciprocating (MMR) micropump. To attain this goal, the Lorentz force, as the actuation mechanism, was used to move a conductive liquid (mercury) slug in a reciprocating manner in order to suck the working fluid (air) from the inlet and pump it to the outlet. The performance of the fabricated MMR micropump was examined in terms of parameters such as pressure...
Analytical modeling of magnetic flux in superconducting synchronous machine
, Article IEEE Transactions on Applied Superconductivity ; Volume 23, Issue 1 , 2013 ; 10518223 (ISSN) ; Elhaminia, P ; Zolghadri, M. R ; Fardmanesh, M ; Sharif University of Technology
2013
Abstract
A general model for superconducting synchronous machines in which the rotor can be considered as a magnetic or a nonmagnetic material is proposed and analytically investigated. Analytical equations for magnetic flux in different regions of the machine have been developed. Furthermore, nonlinear magnetization of the iron core is studied. In order to solve the equations in the case of the iron saturation, a reiterative algorithm is proposed. Finite-element simulation has also been performed to verify the equations and the proposed algorithm. The obtained analytical results show good agreement with finite-element method results
Analytical and numerical study of quantum transport in an array of nanorings: A case study with double rings
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 47 , January , 2013 , Pages 297-302 ; 13869477 (ISSN) ; Khoeini, F ; Sharif University of Technology
2013
Abstract
We present an analytical method to obtain an expression for electron transmission through an array of disordered nanorings (ADNRs) sandwiched between two semi-infinite metallic leads in different lead-ring coupling strengths. Our approach is based on the nearest-neighbor tight-binding approximation and transfer matrix method. First, we derive an analytical formula for electron transmission across the system. Next, we apply our approach to study of the electron transport in a perfect double nanoring (PDNR) and design a NOR gate using the magnetic fluxes inputs. The conductance, current-voltage characteristics and threshold voltage of the system are calculated in the weak and strong coupling...
An analytical approach for optimal design of rotor iron for superconducting synchronous machine
, Article IECON Proceedings (Industrial Electronics Conference), 7 November 2011 through 10 November 2011, Melbourne, VIC ; 2011 , Pages 1741-1745 ; 9781612849720 (ISBN) ; Yazdanian, M ; Zolghadri, M. R ; Fardmanesh, M ; Sharif University of Technology
2011
Abstract
Although iron-cored superconducting machine has been recently proposed in many papers for its advantages over conventional air-cored structure such as less cost and less perpendicular magnetic component on HTS tapes it has not been studied analytically yet. This paper analytically investigates a general model for iron-cored superconducting synchronous machine. In this paper, analytical equations for magnetic flux in different regions of machine have been proposed along with an algorithm to solve the equations. The analytical equations will be then used to optimize the thickness of rotor iron in order to maximize the machine power density. Analytical and finite element simulation results will...
Approximating the distribution of flaws in magnetic materials using the generalized inverse
, Article 2011 IEEE International Conference on Imaging Systems and Techniques, IST 2011 - Proceedings, 17 May 2011 through 18 May 2011, Batu Ferringhi ; May , 2011 , Pages 137-141 ; 9781612848969 (ISBN) ; Abdollahi Jahdi, S ; Norouzi, E ; Sharif University of Technology
2011
Abstract
Non-destructive identification of voids in ferromagnetic materials is of great importance for industrial applications. Magnetic flux leakage technique is used here to examine the defected structure. To this end, an inverse problem should be solved in order to infer the location and depth of internal flaws from the measured leaked magnetic signals. Currently generalized inverse method and singular value decomposition are used for solving such inverse problem. Considering the cracks separation has significant effect on the absolute value of magnetic flux leakage signals, we study different distributions of cracks. In this paper, the magnetic dipole model is proposed to reconstruct the extent...
A low complexity scheme for entanglement distributor buses
, Article Quantum Information Processing ; Volume 10, Issue 4 , 2011 , Pages 519-532 ; 15700755 (ISSN) ; Sharif University of Technology
Abstract
For technological purposes and theoretical curiosity, it is very interesting to have a building block that produces a considerable amount of entanglement between on-demand sites through a simple control of a few sites. Here, we consider permanently- coupled spin networks and study entanglement generation between qubit pairs to find low-complexity structures capable of generating considerable entanglement between various qubit pairs.We find that in axially symmetric networks the generated entanglement between some qubit pairs is rather larger than generic networks. We show that in uniformly-coupled spin rings each pair can be considerably entangled through controlling suitable vertices. To...