Neodymium Permanent Magnet Research Articles

Optimized Design of PMSM With Hybrid-Type Permanent Magnet for Improving Performance and Reliability

This paper proposes an optimized design of permanent magnet (PM) synchronous motor (PMSM) using hybrid-type PM for improving the output characteristics and reliability. Here, the hybrid-type PM is defined as using both neodymium PM (Nd-PM) and ferrite PM (Fe-PM) in a rotor. First, a basic design of PMSM is conducted by considering the magnetic equivalent circuit and applying the magnetic characteristic of Fe-PM changed by the reversed flux of Nd-PM. For optimizing the motor using hybrid-type PM, parallel configuration of reluctance factors is helpful for increasing the output characteristics, and it is analyzed by using a finite element method (FEM). In addition, by using an algorithm, an optimized design is suggested for obtaining maximum torque. The performances of target and proposed motors are compared through FEM. Next, the irreversible demagnetization of each motor is analyzed at high and low temperature, and the demagnetization phenomenon of two-type motors is compared for verifying the reliability of the proposed motor. Finally, prototypes of reference and proposed models are developed for evaluating the enhanced performance through comparison between the two motors.

Cost-Effective Experimental Setup for Studies of Spin Seebeck Effect and Electrical Transport in Thermoelectric Materials

In this article, we report on the design of a low-cost, accurate, and easy-to-implement room-temperature experimental setup to comprehensively study the spin Seebeck effect (SSE) in ferrimagnetic insulators (FIs). Neodymium permanent magnets (NdPMs) are used to generate a fixed uniform magnetic field while the sample is staged in a custom-designed vacuum chamber containing thermal baths (for generating the required temperature gradient) and a complete 360° sample rotation mechanism (for studying the magnetic field angle dependence). Our experiments reveal excellent magnetic field uniformity (±1%) formed between the magnet poles, a highly accurate temperature gradient stability (±1%), and excellent agreement of the longitudinal SSE (LSSE) response for the Pt/YIG structure studied here with those reported in the literature. We also measure the anomalous Nernst effect (ANE) exhibited in a graphite sample, demonstrating the capability of our setup to accurately measure this parameter. Finally, we demonstrate that our setup can also be used to measure the conventional Seebeck effect (SE) and the electrical resistivity of commercially obtained Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> samples, making it a versatile tool for the broad characterization of thermoelectric materials.

Data acquisition system for MAET with magnetic field measurements

Magneto-acousto-electrical tomography (MAET) is an imaging modality to image the electrical conductivity of biological tissues. It is based on electrical current induction by using ultrasound under a static magnetic field. The aim of this study is to develop a data acquisition system for MAET based on magnetic field measurements. The static magnetic field is generated by six permanent neodymium magnets. A 16-element linear phased array (LPA) transducer is utilized to generate acoustic pressure waves inside the phantom. To measure the magnetic field intensity generated by the induced currents, contactless receiver sensors are developed using two similar disk multiple layer coils, which are Helmholtz coil sensor. Physical properties and electrical characteristics of the sensors are assessed. A two-stage cascaded amplifier is designed and utilized in the receiving system. The gain of the cascaded amplifier at 1 MHz is adjusted to be 96 dB. Experimental studies are conducted with two different phantoms, having 3 S m−1 and 58 S m−1 electrical conductivity, respectively. A-scan and B-scan images of phantoms are obtained with the LPA transducer. Comparison of the ultrasound (A-scan) and MAET signals reveals that 3 S m−1 conductive inhomogeneity can be detected with this data acquisition system. Furthermore, the front and rear interfaces of an inhomogeneity () of 58 S m−1 conductivity are detectable.

Trajectory control of electron beams using high intensity permanent magnests for linac-adaptable convergent beam radiotherapy

Convergent beam radiotherapy, or CBRT, currently under development is based on the adaptation of a linear accelerator (linac) to a device which allows to dynamically curve the original trajectory of the electron beam so that it impacts upon a target. This produces a photon beam via Bremsstrahlung which converges on a predetermined focus point (isocenter). Adaptation of the RTHC device is only possible if it is sufficiently compact, as the device must be placed between the linac head exit and the gurney. This requires that new magnetic deflection devices be developed. This paper describes the theoretical and experimental development of controlled-deflection electron beam systems (at energies in MeV ranges) generated in a dual linear accelerator waveguide. A device which follows RTHC geometry is adapted for the system, using new magnetic deflector designs based on permanent neodymium magnets which reach magnetic field intensities in the order of Tesla. The methodology that was developed includes calculations of the radii of curvature with relativistic considerations for mono- and poly-energetic electrons. Deflection angles were calculated based on this theoretical foundation, using a program developed in MatLab® which shows the trajectory of electrons both under ideal conditions (uniform magnetic field) and real conditions (magnetic field defined through intensity distribution). Monte Carlo simulation subroutines were implemented in order to estimate the spectrum of electrons issuing from the linac as well as to directly determine the electron beam trajectory with magnetic deflectors present. Theoretical and simulated results were compared to experiments performed with a clinical linear accelerator, demonstrating correspondence between different methodologies and confirming the ability to achieve electron beam deflection levels necessary for implementation of convergent beam radiotherapy device.

The Influence of Magnetic Fields (0.05 T ≤ B ≤ 7 T) on the Response of Personal Thermoluminescent Dosimeters to Ionizing Radiation

We investigated the main question of whether thermoluminescent dosimeters indicate the correct dose when exposed to magnetic fields from low stray fields up to high magnetic resonance imaging fields inside human magnetic resonance imaging scanners (0.05 T ≤ B ≤ 7 T) during and after irradiation. Medical personnel working in radiology, oncology, or nuclear medicine are regularly monitored with thermoluminescent dosimeters. They might also enter the magnetic field of a magnetic resonance imaging scanner while supervising patients as well as during positron emission tomography-magnetic resonance imaging and magnetic resonance imaging-linac integrated imaging systems and will therefore be exposed to the magnetic fields of magnetic resonance imaging scanners and low stray fields of several millitesla outside of the magnetic resonance imaging scanner, not only before and after, but also during irradiation. Panasonic thermoluminescent dosimetry badges and ring dosimeters for personal monitoring were exposed to magnetic fields originating from a 7 T and a 3 T magnetic resonance imaging scanner as well as neodymium permanent magnets. Four different sealed Cs sources were used in two sets of experiments: (1) magnetically induced fading: irradiated thermoluminescent dosimeters (D ≈ 100 mSv) were exposed to a strong magnetic field (B = 7 T) of a human high-field magnetic resonance imaging scanner after irradiation; no magnetically induced fading (magnetoluminescence) for LiBO:Cu or CaSO:Tm was observed; (2) magnetically induced attenuation: thermoluminescent dosimeters were placed during irradiation in a magnetic field for about 60 h; a significantly reduced dose response was observed for LiBO:Cu-interestingly not at maximum B ≈ 7 T but at B ≈ 0.2 T. This experimental observation is possibly relevant especially for medical and technical personnel in nuclear medicine before and during a magnetic resonance imaging scanning procedure. Follow-up studies need to be made to clarify the kinetics of this effect.

Numerical Assessment of Magnetohydrodynamic Heat Flux Mitigation for Pico-Sized Entry Capsule Mockup

The present study focuses on the influence of applied magnetic fields on argon plasma flows to assess the magnetohydrodynamics (MHD) effects on a pico-sized reentry capsule and their potential as a secondary thermal protection system. It was conducted with numerical methods, using the MHD code SAMSA. Different design adaptations for the capsule were created to integrate neodymium permanent magnets into its nose cone. The adapted design was then modeled in SAMSA, and simulations were carried out for freestream cases and one ground-based test scenario in a plasma wind tunnel, with varying standardized magnetic field strengths between 0.1 T and 1.0 T, and using argon as a working gas. To assess the effectiveness of the applied magnetic field as a secondary thermal protection system, the convective heat flux at the stagnation point and along the capsule’s front surface was analyzed. The results show a conclusive influence of MHD effects, with a reduction of the convective heat flux at the stagnation point by up to 57% and a reduction of the overall heat flux across the front surface by up to 20%. It is found that the best results with regard to heat flux mitigation are attained at comparatively low to moderate magnetic field strengths.

Optimasi Permanen Magnet Synchronous Machine Berbasis Firefly Algorithm

Magnets always have two poles namely the north pole (north / N) and the south pole (south / S). Just as the magnetic charge of the same magnetic pole repels - rejects and the different magnetic poles pull together. Magnets force magnetic materials such as iron due to the magnetic field. A permanent magnet generator is one of the electric machines that utilize mechanical forces to produce electricity where the generator utilizes a permanent magnet as its rotor. To obtain greater output power can be by changing the number and size of windings, varying neodymium permanent magnets of a certain size and reducing the rotor distance with the stator, so that greater power can be achieved. In this study comparing the design without control, with the PID controller, and with the PID controller detuning with Firefly Algorithm. From the simulation results it was found that the best controller in this study was PID-FA with the best current profile and the best voltage profile with a value of 698.3 rpm at t = 0.0055 seconds and steady state voltage at 700.3 rpm at t = 0.04 seconds.

The effect of adding an axial magnetic field on the expansion of a laser-produced plasma

We use a pulsed ultraviolet laser to ablate a copper target in order to study the effects of adding a permanent and axial magnetic field on the plasma plume expansion. The laser pulse duration is 20 ns, its energy is 150 mJ, and it is focused on a surface of about 1 mm2. The target is inserted at the center of a ring permanent neodymium magnet as we compare data taken with and without the magnetic field using a Langmuir probe that is installed at 2.5 cm from the target but is capable of moving radially. The magnetic field, B, affects the plasma plume by reducing its expansion and by increasing the plasma temperature significantly. We report, and for the first time, the measurement of the average axial as well as the radial electric fields and show that both are enhanced in the presence of a magnetic field. This yields a strong increase in the plasma current and thus that of ohmic heating, which could help in explaining the temperature increase recorded by different groups when a magnetic field is added to the plasma plume expansion.We use a pulsed ultraviolet laser to ablate a copper target in order to study the effects of adding a permanent and axial magnetic field on the plasma plume expansion. The laser pulse duration is 20 ns, its energy is 150 mJ, and it is focused on a surface of about 1 mm2. The target is inserted at the center of a ring permanent neodymium magnet as we compare data taken with and without the magnetic field using a Langmuir probe that is installed at 2.5 cm from the target but is capable of moving radially. The magnetic field, B, affects the plasma plume by reducing its expansion and by increasing the plasma temperature significantly. We report, and for the first time, the measurement of the average axial as well as the radial electric fields and show that both are enhanced in the presence of a magnetic field. This yields a strong increase in the plasma current and thus that of ohmic heating, which could help in explaining the temperature increase recorded by different groups when a magnetic field is added to...

In situ determination of exerted forces in magnetic pulling cytometry.

Localized application of exogenous forces on soft biomaterials and cells is often essential for the study of their response to external mechanical stimuli. Magnetic means of applying forces, particularly those based on permanent magnets and magnetic beads coupled to substrates or cells provide an accessible means of exerting forces of appropriate magnitude. The amount of force exerted, however, is often inferred from calibration performed ex situ, with typically similar but different magnetic beads. Here, we construct a simple magnetic tweezer by coupling a pencil-shaped stainless-steel probe to permanent neodymium magnets using a 3D printed adapter. We then demonstrate the in situ determination of magnetic bead pulling forces on a super-paramagnetic micro-bead coupled to a soft substrate using traction force microscopy. We determine the force exerted on the magnetic bead by the magnet probe – and thus exerted by the magnetic bead on the soft polyacrylamide substrate – as a function of the distance between the probe tip and the magnetic bead. We also show that we can determine the force exerted on a magnetic bead coupled to a cell by the changes in the traction force exerted by the cell on the soft substrate beneath. We thus demonstrate that forces of nanonewton magnitude can be locally exerted on soft substrates or cells and simultaneously determined using traction force microscopy. Application of this method for the in situ measurement of localized exogenous forces exerted on cells can also enable dissection of cellular force transmission pathways.

DESIGN AND REALIZATION OF GRIPPERS WITH PERMANENT MAGNETS

Urgency of the research. Modern production requires simple and inexpensive component solutions for gripping large parts. The design of gripping elements using a permanent magnet in this aspect is a promising direction. Target setting. The aim of the project was to realize a gripping component from a commercially available pneumatic drive supplemented with a neodymium permanent magnet and to revive the resulting assembly with a pneumatic portal manipulation device designed for educational activities at the department. Actual scientific researches and issues analysis. Implementation of the project required a detailed market research focused on the tentacles of a similar concept and the study of the principles and properties of permanent magnets. By analyzing the information the project objective was optimized - design of cheap and reliable gripping element. Uninvestigated parts of general matters defining. Available components were used for the resulting solution, with an emphasis on low acquisition costs. This was due to the fact that the output was intended for laboratory use. The research objective. The aim of the research was to build a real functioning and reliably working gripping device usable as an object for educational activities in the education of our students. The statement of basic materials. Design and practical implementation of the grippers with permanent magnets for gripping parts represented in the work. Activation and control of the grips is implemented by compressed air. The implementation of the output confirmed the correctness of considerations as well as the feasibility of the repeatability of this output while meeting the basic requirement for low costs. The project was based on the principles offered by leading companies, but the implementation output gives a higher gripping force at lower input costs. In addition, it provides the possibility of extension to the size range according to customer requirements. Conclusions. The project was successful and its implementation also contributed to the improvement of the educational process at the department, which was one of the monitored benefits. It provides an illustrative demonstration of the possibilities of performing manipulation tasks with non-standard objects.

A Permanent-Magnet Beam Deflector with Tunable Deflection Angle

A beam deflector formed by two modules of permanent dipole magnets is proposed. Each module is assembled of permanent neodymium (NdFeB) magnets as magnetic elements. The design allows for controlling the absolute value and azimuth of the beam-deflection angle by rotating the modules with respect to each other. The proposed device can be used as a beam-trajectory corrector. Compared to existing beam correctors, the proposed device has smaller dimensions for a given field integral, is more reliable, and needs lower running costs.

Design and development of magnetic refrigeration prototype for the performance analysis of magnetocaloric materials

Magnetic refrigeration (MR) has been receiving an attention as an alternative system to conventional refrigeration based on vapor compression. Normally, the vapor compression uses hydrofluorocarbons (HFC) and Chlorofluorocarbons (CFC) as refrigerant fluids which damage ozone layers causing global warming. Consequently, the magnetic system has been developed to replace the traditional system to reduce global warming potential (GWP). The alternative cooling technology is based on the magnetocaloric effect (MCE) of magnetocaloric materials (MCM) which are able to change their temperature following magnetic flux density under magnetic field generator. The refrigeration is operated via an active magnetic regeneration (AMR) cycle with rotating magnets. In this work, the magnet assembly has been designed and studied with the aspiration for compact and efficiency. Based on extensive reviews, the magnet assembly model of Okamura et al. provides the conceptual design with optimal compactness and efficiency. Hence, in this study, the magnet assembly design has been developed based on the model by Okamura et al. The magnetic system consists of a soft magnetic composite stator and four neodymium (NdFeB) permanent magnets rotated by motor. The magnetic field performance of the assembly is analyzed using the COMSOL Multiphysics software. The generated magnetic flux density is 0.65 T provided by only 0.9 L of permanent magnets. In addition, the efficiency of the magnet design is represented by a figure of merit parameter, Λcool. Among others, the proposed design exhibit a high Λcool value of 0.17, which is as high as five times better than the magnet assembly designs by prior work.

Non-contact auxiliary fixture for machining stability improvement of thin flexible workpieces using eddy currents

Thin flexible parts are widely used in the aerospace industry and require a more precise surface finish. The main problem in achieving high-quality product is the vibration induced during machining of thin-walled parts. Clamping these thin parts or using rigid supports for parts, such as for propeller blades, lead to distortion. This issue may be solved using a non-contact auxiliary fixture. The new fixture developed in this research is an eddy current damper for passive control of vibrations in electrically conducting workpieces, using neodymium permanent magnets without any external power source. Two thin aluminum beams with different cross-section and same length were used to test the developed fixture. To increase the overall damping, conducting sheets were attached at the free end of beams. Impact and machining tests were conducted to validate the new fixture. The results showed higher damping and better machining stability leading to enhanced surface quality of the workpiece.

Characterization of magnetic particle alignment in photosensitive polymer resin: A preliminary study for additive manufacturing processes

Material jetting 3D printing is an additive manufacturing technique that allows producing complex parts without tooling and minimum material wastage. In this study, orientation control of randomly shaped, anisotropic hard magnetic ferrite particles is demonstrated for material jetting-based additive manufacturing processes using a developed particle alignment configuration. Strontium ferrite and PR-48 photosensitive resin were used as the base materials. An automated experimental setup with two neodymium permanent cube magnets capable of generating a dipolar magnetic field was built to align magnetic particles in the resin. Particle alignment was characterized for directionality using images obtained through real time optical microscopy. The orientation of magnetic particles was observed to be dependent on the distance of separation between the cube magnets and the magnetization time. X-ray diffraction was used to indicate the c-axis alignment of the hexagonal strontium ferrite particles in the cured specimens. The influence of process parameters on particle orientation was evaluated, employing a full factorial experiment analysis. This fundamental research serves as a basis for constructing and optimizing the magnetic particle alignment setup for additive manufacturing processes.

Optimasi Permanen Magnet Synchronous Machine Berbasis Firefly Algorithm

Magnets always have two poles namely the north pole (north / N) and the south pole (south / S). Just as the magnetic charge of the same magnetic pole repels - rejects and the different magnetic poles pull together. Magnets force magnetic materials such as iron due to the magnetic field. A permanent magnet generator is one of the electric machines that utilize mechanical forces to produce electricity where the generator utilizes a permanent magnet as its rotor. To obtain greater output power can be by changing the number and size of windings, varying neodymium permanent magnets of a certain size and reducing the rotor distance with the stator so that greater power can be achieved. In this study comparing the design without control, with the PID controller, and with the PID controller detuning with Firefly Algorithm. From the simulation results, it was found that the best controller in this study was PID-FA with the best current profile and the best voltage profile with a value of 698.3 rpm at t = 0.0055 seconds and steady state voltage at 700.3 rpm at t = 0.04 seconds.

Experimental Analysis of Charging Characteristics of HTS Field Coils With HTS Contactless Rotary Excitation Device Considering Various HTS Loads

In this paper, the charging characteristics of high-Tc superconducting (HTS) field coils are analyzed experimentally to verify the efficiency of using HTS contactless rotary excitation devices (CREDs). The HTS CRED is composed of eight HTS rotor strands, which are connected in series with HTS load coils, and eight neodymium permanent magnets (N50). The magnetic field of N50 is approximately 0.14 T when the air gap between the HTS rotor strand and N50 is 8 mm. In order to verify the proper charging method, two types of experiments are performed. In the first experiment, the HTS loads are connected in series and are charged by eight HTS rotor strands of the HTS CRED. In the second, the HTS loads are located along the same axis, and each coil is charged by four HTS rotor strands of the HTS CRED. In these experiments, the currents flowing through the HTS loads are measured for rotor speeds ranging from 50 to 300 r/min.

Optimization Design of PMSM With Hybrid-Type Permanent Magnet Considering Irreversible Demagnetization

This paper proposes optimization design of permanent-magnet synchronous motor (PMSM) using hybrid-type permanent magnet (PM) considering irreversible demagnetization. Here, the hybrid-type PM is defined as using both of neodymium PM (Nd-PM) and ferrite PM (Fe-PM) in a rotor. First, irreversible demagnetization of Fe-PM occurring by reversed magnetic field of Nd-PM is analyzed by using a finite-element method, when a rotor is inside or without a stator in order to improve reliability of PMSM using hybrid-type PM. Second, the optimized design considering demagnetization phenomenon is suggested for analyzing exactly output characteristics of the motor using hybrid-type PM. Finally, the prototypes based on proposed design are developed for evaluating the performance and demagnetization phenomenon through experiment.

Magnet assisted composite manufacturing: A novel fabrication technique for high‐quality composite laminates

A novel fabrication method, Magnet Assisted Composite Manufacturing (MACM), is developed to produce high‐quality composite laminates out of an autoclave. This technique involves the placement of high‐temperature Neodymium permanent magnets on a vacuum bag to generate sufficiently high consolidation pressure during cure, thus eliminating the necessity of using an autoclave. The objective of this study is to demonstrate the ability of MACM to fabricate high‐performance laminates, which have comparable mechanical properties, fiber volume fraction, and void content to those achieved by autoclave curing. Towards this goal, eight‐ply, woven carbon/epoxy laminates were fabricated in an oven by MACM and in an autoclave using the same thermal cycle. The thickness of the laminates cured by MACM indicated that an effective consolidation pressure of 0.29 MPa (42 psi) can be generated by the magnets during cure at 177°C (350°F). The high flexural properties, high fiber volume fraction, and the low void content of the laminates fabricated by MACM validated the feasibility of this process as a lower‐cost alternative to autoclave cure, without compromising the part quality. Considerable reduction of void content to under 1% was also achieved by applying magnets during cure when the resin viscosity was at a minimum. POLYM. COMPOS., 40:159–169, 2019. © 2017 Society of Plastics Engineers

Realization of The Adjusting System in Stiffness Compensator Based on Permanent Neodymium Magnets

In this paper one of the cases of adjusting system for the stiffness compensator based on permanent magnets with changing of the axial distance between magnets has been described. The dependency of the traction force from value of the rotation angle of the anchor relatively basis in stiffness compensator has been described. Research & Development is under the scholarship of the President of Russian Federation, order No 184 from 10th of March 2015.

A magneto-fluidic nanoparticle trapping platform for surface-enhanced Raman spectroscopy.

A microfluidic device utilizing magnetically activated nickel (Ni) micropads has been developed for controlled localization of plasmonic core-shell magnetic nanoparticles, specifically for surface enhanced Raman spectroscopy (SERS) applications. Magnetic microfluidics allows for automated washing steps, provides a means for easy reagent packaging, allows for chip reusability, and can even be used to facilitate on-chip mixing and filtration towards full automation of biological sample processing and analysis. Milliliter volumes of gold-coated 175-nm silica encapsulated iron oxide nanoparticles were pumped into a microchannel and allowed to magnetically concentrate down into 7.5 nl volumes over nano-thick lithographically defined Ni micropads. This controlled aggregation of core-shell magnetic nanoparticles by an externally applied magnetic field not only enhances the SERS detection limit within the newly defined nanowells but also generates a more uniform (∼92%) distribution of the SERS signal when compared to random mechanical aggregation. The microfluidic flow rate and the direction and strength of the magnetic field determined the overall capture efficiency of the magneto-fluidic nanoparticle trapping platform. It was found that a 5 μl/min flow rate using an attractive magnetic field provided by 1 × 2 cm neodymium permanent magnets could capture over 90% of the magnetic core-shell nanoparticles across five Ni micropads. It was also observed that the intensity of the SERS signal for this setup was 10-fold higher than any other flow rate and magnetic field configurations tested. The magnetic concentration of the ferric core-shell nanoparticles causes the SERS signal to reach the steady state within 30 min can be reversed by simply removing the chip from the magnet housing and sonicating the retained particles from the outlet channel. Additionally, each magneto-fluidic can be reused without noticeable damage to the micropads up to three times.