scispace - formally typeset
Search or ask a question

Showing papers in "IEEE Transactions on Magnetics in 2001"


Journal ArticleDOI
TL;DR: In this article, the design and performance of a magnetic gear, which employs rare-earth magnets, has been described, which simulation studies have shown to have a transmitted torque density exceeding 100 kNm/m/sup 3.
Abstract: Mechanical gearboxes are used extensively to match the operating speed of prime-movers to the requirements of their loads. Although, high system torque densities can be achieved, gear lubrication and cooling are often required, whilst noise, vibration and reliability can be significant issues. The paper describes the design and performance of a magnetic gear, which employs rare-earth magnets, which simulation studies have shown to have a transmitted torque density exceeding 100 kNm/m/sup 3/.

943 citations


Journal ArticleDOI
TL;DR: The magnetostriction of b.c. Fe is increased over 10-fold at room temperature by the substitution of /spl sim/20% gallium for Fe as mentioned in this paper.
Abstract: The magnetostriction (/spl lambda//sub 100/) of b.c.c. Fe is increased over 10-fold at room temperature by the substitution of /spl sim/20% gallium for Fe. Fe/sub 1-x/Ga/sub x/ alloys with x between 0.19 and 0.214 that are quenched from 800/spl deg/C exhibit magnetostrictions /spl sim/25% higher than those furnace-cooled at 10/spl deg//min. We propose that this great increase of magnetostriction above that of Fe in Fe-Ga alloys is not due to conventional magnetoelastic effects but due to the substitutive presence of asymmetrically shaped clusters of the Ga atoms. As the concentration of solute atoms approaches 25%, the lattice becomes relaxed with formation of a more ordered structure and the magnetostriction decreases in value.

253 citations


Journal ArticleDOI
TL;DR: The dynamic change of crossover and mutation probabilities, the space reduction and the global elitism during the evolution process show that great improvement can be achieved for all GA types.
Abstract: This paper presents an exhaustive study of the Simple Genetic Algorithm (SGA), Steady State Genetic Algorithm (SSGA) and Replacement Genetic Algorithm (RGA). The performance of each method is analyzed in relation to several operators types of crossover, selection and mutation, as well as in relation to the probabilities of crossover and mutation with and without dynamic change of its values during the optimization process. In addition, the space reduction of the design variables and global elitism are analyzed. All GAs are effective when used with its best operations and values of parameters. For each GA, both sets of best operation types and parameters are found. The dynamic change of crossover and mutation probabilities, the space reduction and the global elitism during the evolution process show that great improvement can be achieved for all GA types. These GAs are applied to TEAM benchmark problem 22.

248 citations


Journal ArticleDOI
TL;DR: In this paper, high temperature solution phase decomposition of Fe(CO)/sub 5/ and reduction of Pt(acac)/sub 2/ in the presence of stabilizers, oleic acid and oleyl amine, are employed to produce 4 nm diameter FePt nanoparticles.
Abstract: High temperature solution phase decomposition of Fe(CO)/sub 5/ and reduction of Pt(acac)/sub 2/ in the presence of stabilizers, oleic acid and oleyl amine, are employed to produce 4 nm diameter FePt nanoparticles. The Fe and Pt composition of the nanoparticle materials can be tuned by adjusting the molar ratio of Fe(CO)/sub 5/ to Pt(acac)/sub 2/, and the compositions ranging from Fe/sub 30/Pt/sub 70/ to Fe/sub 80/Pt/sub 20/ are obtained. The nanoparticle materials are easily dispersed into alkane solvent, facilitating their self-organization into nanoparticle superlattices. As synthesized FePt nanoparticles possess a disordered fcc structure and show superparamagnetic behavior. Thermal annealing induces a change of internal particle structure and thus of the magnetic properties of the particles. Composition dependent structure analysis shows that an annealed FePt nanoparticle assembly with a composition around Fe/sub 55/Pt/sub 45/ will lead to the highly ordered fct phase. This Fe/sub 55/Pt/sub 45/ nanoparticle assembly yields high coercivity, and will be a candidate for future ultra-high density magnetic recording media applications.

247 citations


Journal ArticleDOI
TL;DR: In this article, a new eddy-current testing technique for surface or near-surface defect detection in nonmagnetic metals using giant magnetoresistive (GMR) sensors is introduced.
Abstract: The purpose of this paper is to introduce a new eddy-current testing technique for surface or near-surface defect detection in nonmagnetic metals using giant magnetoresistive (GMR) sensors. It is shown that GMR-based eddy-current probes are able to accurately detect short surface-breaking cracks in conductive materials. The self-rectifying property of the GMR sensor used in this study leads to a simplified signal conditioning circuit, which can be fully integrated on a silicon chip with the GMR sensor. The ability to manufacture probes having small dimensions and high sensitivity (220 mV/mT) to low magnetic fields over a broad frequency range (from dc up to 1 MHz) enhances the spatial resolution of such an eddy-current testing probe. Experimental results obtained by scanning two different probes over a slotted aluminum specimen are presented. General performance characteristics are demonstrated by measurements of surface and subsurface defects of different sizes and geometries. Dependence of the sensor output on orientation, liftoff distance, and excitation intensity is also investigated.

211 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analytically revealed that the cogging torque can be reduced by controlling N/sub L/th harmonic components of the square of airgap permeance function and flux density function.
Abstract: Using energy method, this paper analytically reveals that the cogging torque can be reduced by controlling N/sub L/th harmonic components of the square of airgap permeance function and flux density function, where N/sub L/ denotes the least common multiple of number of poles and number of slots. As for design tools, it introduces various design techniques to reduce cogging torque with analytical formulation and FEM examples.

201 citations


Journal ArticleDOI
TL;DR: In this paper, the design and analysis of a doubly salient permanent magnet (DSPM) motor is presented, and the corresponding output power equation is analytically derived, where the leakage flux outside the stator circumference of the DSPM motor is firstly taken into account.
Abstract: This paper presents the design and analysis of a new doubly salient permanent magnet (DSPM) motor. The corresponding output power equation is analytically derived. The initial calculation of motor dimensions and parameters, namely, the core diameter, stack length, permanent magnet size, and winding turns, are also discussed. An 8/6-pole DSPM motor is designed and built for exemplification. Moreover, finite element analysis of this motor is carried out to investigate the magnetic field distribution at different rotor positions and load currents, in which the leakage flux outside the stator circumference of the DSPM motor is firstly taken into account. Hence, the characteristics of the proposed motor are deduced. Experimental results of the prototype are given to verify the theoretical analysis and to confirm its high efficiency.

194 citations


Journal ArticleDOI
TL;DR: In this paper, an analytical model of losses in round Litz wire windings is presented based on exact analytical equations for round conductors, and it closely includes the distribution of the leakage field across the winding space.
Abstract: An accurate analytical model of losses in round Litz wire windings is presented. The model is based on the exact analytical equations for round conductors, and it closely includes the distribution of the leakage field across the winding space. A closed-form formula of the ac resistance of round Litz wire windings is developed from the model. An analytic solution of the optimal value of the ac resistance is derived. The expression of the strand dimension corresponding to the optimal value of the ac resistance is also determined.

181 citations


Journal ArticleDOI
TL;DR: In this paper, two mutually orthogonal coils fed with phase-quadrature currents comprise the excitation source, which is equal to a mechanically rotating magnetic dipole, and the resulting excitation field rotates elliptically at any position in the near field region.
Abstract: The method is based on two-axis generation of a quasi-static rotating magnetic field and three-axis sensing. Two mutually orthogonal coils fed with phase-quadrature currents comprise the excitation source, which is equal to a mechanically rotating magnetic dipole. The resulting excitation field rotates elliptically at any position in the near-field region. The AC part of the squared field magnitude is a sinusoidal wave at twice the excitation frequency. The following set of parameters uniquely characterize the excitation at the sensor's position: the phase of the squared field waveform, relative to the excitation currents, the minimum field value, the ratio of the field extremes, and the orientation of the excitation field plane. Simple and explicit analytical expressions are given which relate the first three parameters to the azimuth, elevation, and distance from the source to the sensor, respectively. The orientation of the sensor axes, relative to the plane of the excitation, can easily be determined by comparing the phase and amplitude of the measured signals against the phase and amplitude of the excitation field at the sensor's position. Apart from simplicity, the proposed method increases the speed of tracking; a single period of excitation is in principle sufficient to obtain all of the information needed to determine both the sensor's position and orientation. A continuous sinusoidal excitation mode allows an efficient phase-locking and accurate detection of the sensor output. It also improves the electromagnetic compatibility of the method.

168 citations


Journal ArticleDOI
TL;DR: In this article, the magnetization dynamics of soft ferromagnetic thin films can be tuned using rare-earth (RE) dopants, and low concentrations of Tb in 50 nm Ni/sub 81/Fe/sub 19/ films are found to increase the Gilbert magnetic damping parameter /spl alpha/ over two orders of magnitude without great effect on easy axis coercivity or saturation magnetization.
Abstract: We show that the magnetization dynamics of soft ferromagnetic thin films can be tuned using rare-earth (RE) dopants. Low concentrations (2 to 10%) of Tb in 50 nm Ni/sub 81/Fe/sub 19/ films are found to increase the Gilbert magnetic damping parameter /spl alpha/ over two orders of magnitude without great effect on easy axis coercivity or saturation magnetization. Comparison with Gd dopants indicates that the orbital character of the Tb moment is important for transferring magnetic energy to the lattice. Structural transformations from the crystalline to the amorphous state, observed over the first 2%-10% of RE doping, may play a contributing but not sufficient role in damping in these films. The approach demonstrated here shows promise for adjusting the dynamical response, from underdamped to critically damped, in thin film materials for magnetic devices.

135 citations


Journal ArticleDOI
TL;DR: The paper proposes a modification to the Jiles-Atherton model to allow improved accuracy in the modeling of the major loop and introduces the concept of simultaneous optimization for major and minor hysteresis loops to ensure accurate model optimization over a wide variety of operating conditions.
Abstract: Modeling magnetic components for simulation in electric circuits requires an accurate model of the hysteresis loop of the core material used It is important that the parameters extracted for the hysteresis model be optimized across the range of operating conditions that may occur in circuit simulation This paper shows how to extract optimal parameters for the Jiles-Atherton model of hysteresis by the genetic algorithm approach It compares performance with the well-known simulated annealing method and demonstrates that improved results may be obtained with the genetic algorithm It also shows that a combination of the genetic algorithm and the simulated annealing method can provide an even more accurate solution than either method on its own A statistical analysis shows that the optimization obtained by the genetic algorithm is better on average, not just on a one-off test basis The paper introduces and applies the concept of simultaneous optimization for major and minor hysteresis loops to ensure accurate model optimization over a wide variety of operating conditions It proposes a modification to the Jiles-Atherton model to allow improved accuracy in the modeling of the major loop

Journal ArticleDOI
TL;DR: In this article, a noncontact suspension of a 3.2 kg flywheel rotor is achieved when it rotates above 20 Hz, and the suspension design addresses some drawbacks of other passive magnetic suspension systems, such as high rotational losses, high manufacturing accuracy, and dynamical problems.
Abstract: This paper proposes a novel type of passive noncontact magnetic suspension. An advantageous feature of passive suspension systems is that they are intrinsically stable, in contrast to active magnetic bearings and therefore can provide much higher reliability, which is known to be the crucial factor in applications requiring continuous noncontact suspension of high-speed rotors. An example of such an application is flywheel energy storage systems, which are considered to be an attractive alternative to conventional electrochemical batteries from both environmental and overall energy efficiency aspects. In such systems, a high-speed rotor is used to accumulate energy in the form of kinetic energy, and its continuous noncontact suspension may be needed for many years with no faults being tolerable. The suspension design addresses some drawbacks of other passive magnetic suspension systems, such as high rotational losses, high manufacturing accuracy, and dynamical problems. The authors have built and tested a bearing prototype, in which noncontact suspension of a 3.2 kg rotor is achieved when it rotates above 20 Hz.

Journal ArticleDOI
TL;DR: The results of the flight and ground experimentation are presented and the challenges for using these strapdown devices on rolling projectiles are described.
Abstract: Low-cost micromachined, inertial measurement sensors have steadily emerged into the commercial marketplace. Some of these sensors were evaluated through ground and flight experiments for their insertion potential into military applications like operational test and evaluation and smart munition guidance. Performance requirements for navigation and time space position information (TSPI) are fast approaching those needed, especially when integrated with a Global Positioning System (GPS). Artillery and rockets, instrumented with "automobile grade" microelectromechanical (MEMS) accelerometers and telemetry units, were recently part of a flight experiment which resulted in good success. The results of a high-g shock study suggest that some of these sensors are rugged enough to survive both low-g and high-g launch. Analyzes of the accelerometer data show good comparison to radar-based acceleration measurements and 6-degree-of-freedom trajectory simulations. Flight simulated ground experimentation with gyroscopes have also been conducted that show promise for measuring projectile pitching and yawing behavior. Recent flight experiments may also be available for comparison to ground based measurement devices. This paper presents the results of the flight and ground experimentation and describe the challenges for using these strapdown devices on rolling projectiles.

Journal ArticleDOI
TL;DR: In this paper, the evolution of crystal structure during annealing at 600/spl deg/C was studied in FePt/C and the dependence of a, c, and c/a on the order of ordering was determined.
Abstract: Nanocomposite FePt/C and FePt/BN thin films have been fabricated by dc and rf magnetron sputtering on naturally-oxidized Si[100] substrates. Particles consisting of the highly anisotropic tetragonal L1/sub 0/ FePt phase were obtained by annealing the as-made multilayers by a conventional vacuum furnace in the temperature range of 500 to 800/spl deg/C. By controlling the annealing conditions, samples with grain size in the range of 3 to 20 nm were obtained, with coercivities between 2 and 16 kOe. The evolution of crystal structure during annealing at 600/spl deg/C was studied in FePt/C and the dependence of a, c and c/a on annealing time were determined. These data were used to estimate the degree of ordering which was found to increase with aging, but with a maximum value less than the bulk value, explaining thus the lower H/sub c/ in the nanoparticles.

Journal ArticleDOI
TL;DR: In this paper, the magnetic fields of a generalized axisymmetric current distribution are given either in closed form as elliptic integral expressions or as integrals of elementary functions over a finite range.
Abstract: An analytical method originally developed for fluid mechanics has been applied to the analogous problem of calculating the magnetic field induced by axisymmetric current sheets, disks, and solenoids. The magnetic fields of a generalized axisymmetric current distribution are given either in closed form as elliptic integral expressions or as integrals of elementary functions over a finite range. The paper concentrates on the analysis of the fields generated by specified current distributions, though the method can also be applied to solve boundary value problems.

Journal ArticleDOI
TL;DR: In this article, the properties and structure of Co-Zr-O nano-granular films prepared by reactive sputtering in an atmosphere of argon and oxygen gases were investigated.
Abstract: A study was made of the properties and structure of Co-Zr-O nano-granular films prepared by rf reactive sputtering in an atmosphere of argon and oxygen gases. We found soft magnetic Co-Zr-O films in a wide compositional range near Co-ZrO/sub 2/ and investigated systematically the compositional dependence of their magnetic properties and electrical resistivity. The films near Co/sub 60/Zr/sub 10/O/sub 30/ simultaneously have anisotropy fields more than 150 Oe, coercivities less than 3 Oe, saturation magnetizations more than 9 kG, and electrical resistivities more than 1000 /spl mu//spl Omega/cm. The frequency response of permeability of these films is excellent. And they show a high resonance frequency exceeding 3 GHz.

Journal ArticleDOI
TL;DR: A new optimal shape design method for microwave passive devices for better performances in a broadband is proposed, which is based on vector finite element time domain (FETD) method and design sensitivity analysis (DSA).
Abstract: In this paper, a new optimal shape design method for microwave passive devices for better performances in a broadband is proposed, which is based on vector finite element time domain (FETD) method and design sensitivity analysis (DSA). The design sensitivity is evaluated using an adjoint variable method. While the original field equation is an initial-value problem, the adjoint equation is an terminal-value problem. To transform the terminal-value problem into a initial-value problem, a backward time scheme is used. To verity its usefulness, a two-dimensional E-plane waveguide T-junction is analyzed.

Journal ArticleDOI
TL;DR: In this article, a dielectric composite consisting of a polymer coated onto a high-density metallized Kraft has been developed for application in pulse power capacitors, which can achieve 2 to 3 J/cm/sup 3/ whole capacitor energy density at voltage levels above 3.0 kV, and can maintain its physical properties to temperatures above 175/spl deg/C.
Abstract: A new dielectric composite consisting of a polymer coated onto a high-density metallized Kraft has been developed for application in pulse power capacitors. The polymer coating is custom formulated for high dielectric constant and strength with minimum dielectric losses. The composite can be wound and processed using conventional wound film capacitor manufacturing equipment. This new system has the potential to achieve 2 to 3 J/cm/sup 3/ whole capacitor energy density at voltage levels above 3.0 kV, and can maintain its physical properties to temperatures above 175/spl deg/C. The technical and manufacturing development of the composite material and fabrication into capacitors are summarized in this paper. Energy discharge testing, including capacitance and charge-discharge efficiency at normal and elevated temperatures, as well as DC life testing were performed on capacitors manufactured using this material. TPL (Albuquerque, NM) has developed the material and Aerovox (New Bedford, MA) has used the material to build and test model capacitors. The results of the testing will focus on pulse power applications specifically those found in electromagnetic armor and guns, high power microwave sources and defibrillators.

Journal ArticleDOI
TL;DR: In this paper, a magnetic circuit model for an interior permanent magnet (IPM) synchronous machine is presented, which includes each portion of magnetic flux paths, especially the leakage flux paths around the magnets in the rotor.
Abstract: This paper presents a magnetic circuit model for an interior permanent magnet (IPM) synchronous machine. The model includes each portion of magnetic flux paths, especially the leakage flux paths around the magnets in the rotor. The magnetic field quantities are expressed analytically in terms of the reluctance ratio /spl beta/ and the leakage flux ratios /spl eta/ and /spl lambda/. It is shown that the width and the iron saturation level of the iron bridge have an important effect on the magnetic field distribution within the motor. Numerical results confirm the validity of the analytical model.

Journal ArticleDOI
TL;DR: In this paper, a new permanent magnet array for planar motor is proposed and the flux density distribution for the array is solved analytically by using the scalar magnetic potential equation.
Abstract: A new permanent magnet array for planar motor is proposed. The flux density distribution for the array is solved analytically by using the scalar magnetic potential equation. It is verified that the performance of the new magnet array is superior to the existing magnet arrays presented in patents.

Journal ArticleDOI
TL;DR: In this paper, the authors used magnetic granular films with thickness of 2/spl mu/m to suppress high frequency conduction noise in the quasimicrowave band.
Abstract: Noise suppression in downsized circuits utilizing magnetic granular films is demonstrated. Films of Fe-Al-O with thickness of 2 /spl mu/m which exhibit very high /spl mu/" dispersion in the quasimicrowave band were found to work as noise suppressors. The films were attached onto a micro-strip line and the transmission characteristics were compared. This work is the first to verify that films with only 2 /spl mu/m thickness can play a role in suppression of high frequency conduction noise in the quasimicrowave band. The results suggest a possibility of thin film noise suppressors which can be integrated into micron scale semiconductor circuits.

Journal ArticleDOI
TL;DR: In this article, the simulation of rotating electrical machines with skewed slots by means of a multi-slice FE model is studied, and particular attention is devoted to the ensuing skew discretization error.
Abstract: The simulation of rotating electrical machines with skewed slots by means of a multi-slice FE model is studied. Particular attention is devoted to the ensuing skew discretization error. As an alternative to the commonly adopted uniform distribution of the cross-sections along the shaft, a Gauss distribution is proposed. The application to a squirrel-cage induction motor under various working conditions shows that the latter distribution produces a considerably smaller discretization error. The calculation results are also compared to experimental data.

Journal ArticleDOI
TL;DR: In this paper, the magnetic properties of bcc-Fe fine particles with a diameter D of 3/spl sim/40 nm prepared by a vapor condensation process were studied. And the particles exhibit uniaxial anisotropy of 2.0/spl times/10/sup 6/ erg/cc which is much larger than that of bulk Fe.
Abstract: We have studied the magnetic properties of bcc-Fe fine particles with a diameter D of 3/spl sim/40 nm prepared by a vapor condensation process. The particles exhibit uniaxial anisotropy of 2.0/spl sim/3.0/spl times/10/sup 6/ erg/cc which is much larger than that of bulk Fe (0.5/spl times/10/sup 6/ erg/cc). Numerical calculations taking into account dipolar interaction and thermal agitation reproduce the particle size dependence of coercivity very well. According to the present work, magnetization reversal of Fe particles proceeds via coherent rotation for D 15/spl sim/20 nm. It is, however, still uncertain why the magnetic anisotropy of Fe fine particles is uniaxial and so large.

Journal ArticleDOI
TL;DR: In this article, a focused ion beam was used to directly pattern thin-film granular perpendicular Co/sub 70/Cr/sub 18/Pt/sub 12/ media.
Abstract: We have used a focused ion beam to directly pattern thin-film granular perpendicular Co/sub 70/Cr/sub 18/Pt/sub 12/ media. By cutting trenches /spl sim/6 nm deep in the /spl sim/20 nm media, we have produced square arrays of magnetically isolated islands with periods in the range 65-500 nm. At periods below /spl sim/130 nm we observe only single magnetic domains, which exhibit a rough "checker-board" pattern upon ac demagnetization. We have patterned at densities of over 140 Gbit/in/sup 2/.

Journal ArticleDOI
Amr A. Adly1
TL;DR: In this article, three-dimensional computations have been carried out on a typical single-phase power transformer using the Hopfield neural network energy minimization technique, as well as comparison with short circuit forces.
Abstract: Inrush currents are frequently encountered during the switching process of transformers. The purpose of this paper is to present an investigation of forces that appear as a result of inrush currents. While both short circuit and inrush transformer situations might seem identical, they vary significantly from the core magnetization viewpoint. Three-dimensional computations have been carried out on a typical single-phase power transformer using the Hopfield neural network energy minimization technique. Results are given in the paper as well as comparison with short circuit forces.

Journal ArticleDOI
TL;DR: In this paper, the radial force density and magnetic unbalanced force for IPM and SPM motors when rotor eccentricity exists were analyzed by Maxwell stress tensor and discrete Fourier transform.
Abstract: The permanent magnet motor is often the most important element in many precision rotor applications and also a frequent source of vibration and acoustic noise. The eccentricity between stator and rotor is inevitably introduced during manufacturing process, such as mass unbalance, shaft bow and bearing tolerances. This paper investigates radial force density and magnetic unbalanced force for IPM and SPM motors when rotor eccentricity exists. For the magnetic field analysis, a finite element method is used to account for the magnetic saturation and rotor eccentricity. The radial force density and magnetic unbalanced force are analyzed by Maxwell stress tensor and discrete Fourier transform. An IPM BLDC motor, mostly chosen to realize high speed operation, is significantly affected by rotor eccentricity due to magnetic saturation.

Journal ArticleDOI
TL;DR: The paper presents the application of a finite element method for predicting the performance of induction motor having electric and magnetic asymmetry of the rotor cage due to some broken rotor bars, and takes into account the magnetic materials nonlinearity.
Abstract: The paper presents the application of a finite element method for predicting the performance of induction motor having electric and magnetic asymmetry of the rotor cage due to some broken rotor bars. Quantities like magnetic vector potential, flux density, force components, rotor and stator currents, mutual and leakage inductance were determined very precisely. The paper takes into account the magnetic materials nonlinearity. The detailed insight in magnetic field distribution of a squirrel cage induction motor forms the basis for further evaluation of its operational behavior. Increasing anomaly in magnetic field distribution due to the increasing number of broken rotor bars results in a degradation of steady-state and dynamic performance of the induction motor and can be determined with computer simulation, eliminating expensive and time consuming laboratory tests. The obtained results are compared with measurements. Correct evaluation of faulty motor performance is a very significant part of condition monitoring and diagnostic procedure in modern supervision systems of electrical drives.

Journal ArticleDOI
TL;DR: The United States Navy is considering the electromagnetic (EM) railgun as a future candidate for long-range shore bombardment missions as mentioned in this paper, and a brief study evaluates the gun and the pulsed power supply for this application.
Abstract: The United States Navy is considering the electromagnetic (EM) railgun as a future candidate for long-range shore bombardment missions. This brief study evaluates the gun and the pulsed power supply for this application. Approximate parameters are derived for a notional system that includes the projectile, launch package, railgun, and pulsed power components.

Journal ArticleDOI
TL;DR: In this article, a new discovery has been made in the field of magnetic materials that manifests itself in the form of a displaced hysteresis loop, which can be turned through 180/spl deg/ and it will still return to its original orientation.
Abstract: A new discovery has been made in the field of magnetic materials that manifests itself in the form of a displaced hysteresis loop. In addition, although from the same basic phenomena, the magnetic material has only one stable orientation in a magnetic field. In particular, it can be turned through 180/spl deg/ and it will still return to its original orientation. The material that exhibits this property is a compact of fine particles of cobalt (100-1000 /spl Aring/) that have a cobaltous oxide coating.

Journal ArticleDOI
TL;DR: An improved meshless method is presented, with an emphasis on the detailed description of this new computational technique and its numerical implementations, by investigating the usefulness of a commonly neglected parameter.
Abstract: An improved meshless method is presented, with an emphasis on the detailed description of this new computational technique and its numerical implementations, by investigating the usefulness of a commonly neglected parameter. Two approaches to enforce essential boundary conditions are also thoroughly investigated. Numerical tests on a mathematical function are carried out as a means of validating the proposed method. It is seen that the proposed method is more robust than the conventional ones. Applications in solving electromagnetic problems are also presented.